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Posted: Mon, Aug 17, 1992 3:05 PM EDT Msg: LGJC-5347-1896
k.mielke(rec),
j.kemper(rec), s.price.prh(rec)
CC: l.miller.ucar(rec), t.whittaker(rec)
Subj: Nat'l tech. info. message
OM23 sent the attached national technical information message (AFOS PIL
WSHPNSNMC; WMO header NOFS10 KWBC) this afternoon. The message announces the
implementation of a tropical cyclone synthetic data system into the global
model on August 18, 1992 at 1200 UTC (tomorrow). This implementation was
approved based on tests NMC's Development has done which indicate that
only one second will be added to the front end processing of the global model.
We continue to closely monitor, and restrict when necessary, all
implementations on the front end computers, until additional computer
resources are available.
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WSHPNSNMC
NOFS10 KWBC 171803
NATIONAL TECHNICAL INFORMATION MESSAGE 92-06
NATIONAL WEATHER SERVICE HEADQUARTERS
200 PM EDT MON AUG 17 1992
TO: ALL NWS OFFICES
DOMESTIC DATA SERVICE USERS
FROM: MARY M. GLACKIN
CHIEF, SERVICES DEVELOPMENT BRANCH
SUBJECT: INTRODUCTION OF SYNTHETIC TROPICAL CYCLONE
OBSERVATIONS INTO THE NATIONAL
METEOROLOGICAL CENTER (NMC) GLOBAL MODEL
ANALYSES
(THE FOLLOWING INFORMATION WAS PROVIDED BY DR. STEPHEN LORD OF
THE REGIONAL AND MESOSCALE MODELING BRANCH OF NMC).
ON TUESDAY, AUGUST 18, 1992, AT 1200 UTC, NMC WILL IMPLEMENT
A TROPICAL CYCLONE SYNTHETIC DATA SYSTEM (SDS) INTO ALL GLOBAL
MODEL ANALYSES (AVIATION AND FINAL). GLOBAL MODEL RESOLUTION,
DUE TO RECENT INCREASES, NOW ENABLE TROPICAL CYCLONE (TC)
TRACK FORECASTS. THE PURPOSE OF ADDING SYNTHETIC DATA TO THE
GLOBAL FORECAST SYSTEM IS TO REDUCE ERRORS IN THE INITIAL
POSITION, SIZE AND INTENSITY OF TROPICAL DISTURBANCES, AND TO
IMPROVE GLOBAL MODEL FORECAST ERRORS. THE SDS WILL CORRECTLY
POSITION A CYCLONE-LIKE VORTEX IN THE GLOBAL MODEL ANALYSES
AND WILL TRACK THIS VORTEX THROUGHOUT THE MODEL FORECAST.
THE SDS CONSISTS OF THREE PARTS: THE GUESS FIELD SCANNER; THE
SYNTHETIC DATA MAKER; AND THE VORTEX TRACKER. INPUT DATA ARE
STORM POSITIONS, CURRENT MOTION, AND VARIOUS STRENGTH AND SIZE
PARAMETERS SUCH AS THE CENTRAL PRESSURE AND THE RADIUS OF THE
OUTERMOST CLOSED ISOBAR OF TROPICAL DISTURBANCES. THESE DATA
ARE SUPPLIED BY TROPICAL CYCLONE WARNING CENTERS THROUGHOUT
THE WORLD: THE NATIONAL HURRICANE CENTER (MIAMI); THE JOINT
TYPHOON WARNING CENTER (GUAM); AND THE AUSTRALIA DARWIN
REGIONAL METEOROLOGICAL CENTER.
THE GUESS FIELD SCANNER FINDS A VORTEX SIGNATURE IN THE
ANALYSIS GUESS FIELD AND REPORTS THIS POSITION TO THE
SYNTHETIC DATA MAKER. THE SCANNER LOOKS FOR MINIMUM VALUES IN
THE HEIGHT FIELDS AND WIND SPEED AND A MAXIMUM VALUE IN THE
RELATIVE VORTICITY FIELD AT BOTH 1000 AND 850 MB IN THE
VICINITY OF THE REPORTED STORM POSITION. POSITIONS OF THESE
MINIMA AND MAXIMA ARE COMBINED INTO A CONSENSUS POSITION AFTER
OUTLYING POSITIONS ARE REMOVED.
THE SYNTHETIC DATA MAKER PRODUCES WIND-ONLY SOUNDINGS FROM THE
TROPICAL CYCLONE STRENGTH AND SIZE PARAMETERS AND ADDS THESE
SOUNDINGS TO THE DATA BASE FOR THE SPECTRAL STATISTICAL
INTERPOLATION (SSI) ANALYSIS. THE SOUNDINGS EXTEND ONLY AS
DEEP AS THE REPORTED STORM CYCLONIC MOTION AND ARE ON
MANDATORY PRESSURE SURFACES.
THE VORTEX TRACKER WORKS ON THE SAME PRINCIPLES AS THE GUESS
FIELD SCANNER DESCRIBED ABOVE EXCEPT THAT POSITIONS ARE
DIAGNOSED EVERY 12 HOURS FROM THE ANALYSIS OUT TO 72 HOURS.
IN ADDITION, THE MAXIMUM 850 MB WIND SPEED IN THE VICINITY OF
THE STORM IS DETERMINED. DIAGNOSED TRACKS ARE REPORTED TO THE
NATIONAL HURRICANE CENTER AND ARE ADDED TO AN ON-LINE TRACK
ARCHIVE.
FORECAST IMPLICATION:
--------------------
BASED ON TEST RUNS WITH THE TRIANGULAR 126 (T126) TRUNCATION
GLOBAL MODEL AND STORM DATA FROM THE 1989-1990 HURRICANE
SEASONS, THE IMPACT ON THE 3 DAY GLOBAL MODEL FORECAST WAS
SMALL. ANOMALY CORRELATIONS FOR 500 MB HEIGHT WERE EQUIVALENT
IN THE NORTHERN HEMISPHERE AND SLIGHTLY IMPROVED IN THE
SOUTHERN HEMISPHERE. THE SDS MAY HAVE AN IMPACT ON HURRICANE
FORECAST MODELS, SUCH AS THE QUASI-LAGRANGIAN (QLM), THAT USE
GLOBAL MODEL FIELDS. TESTS SHOW THAT THE EXACT IMPACT ON THE
QLM IS VERY HARD TO PREDICT, WITH SOME CASES ABOUT 10-20%
IMPROVED BUT OTHERS ABOUT 10% WORSE.
PROCEDURES HAVE BEEN DEVELOPED AT NMC TO REMOVE THE SYNTHETIC
DATA FROM A PARTICULAR MODEL RUN IF THE ANALYSES IS DEEMED
ABNORMAL AS A RESULT OF SYNTHETIC DATA. THE SENIOR DUTY
METEOROLOGIST (SDM) WILL BE RESPONSIBLE FOR THE MONITORING AND
REMOVAL OF IN-APPROPRIATE OR ERRONEOUS SYNTHETIC DATA.
A TECHNICAL PROCEDURES BULLETIN PROVIDING ADDITIONAL DETAILS
ON THE SDS IS BEING PREPARED.
END
SENT - W/OM23
NNNN
Posted: Tue, Aug 18, 1992 3:12 PM EDT Msg: KGJC-5348-5267
k.mielke(rec),
j.kemper(rec), s.price.prh(rec)
CC: l.miller.ucar(rec), t.whittaker(rec)
Subj: CAC press release
Shirley Matejka sent the following message on AFOS, NWWS, Domestic Data
Service, International data Service, Canadian AES, Honolulu (via NWSTG), and
ISPAN this afternoon.
-------------------------------------------------------------------------
ZCZC WSHPNSNMC
TTAA00 KWSH DDHHMM
PUBLIC INFORMATION STATEMENT
CLIMATE ANALYSIS CENTER/NMC
235 PM EDT TUE AUG 18 1992
NORTH AMERICAN CLIMATE ADVISORY 92/1
CURRENT GROWING SEASON ASSESSMENT
AUGUST 17, 1992
EXECUTIVE SUMMARY
SINCE LATE 1991, BOTH LONG AND SHORT-TERM PRECIPITATION
DEFICITS, ALONG WITH ABNORMALLY HIGH TEMPERATURES, HAVE
PRODUCED ADVERSE CONDITIONS IN MUCH OF THE WESTERN U.S. AND
SOUTHWESTERN CANADA. THIS HAS FURTHER EXACERBATED THE
SITUATION IN SOME AREAS THAT HAVE EXPERIENCED UP TO SEVEN
YEARS OF INADEQUATE WINTER PRECIPITATION. AS A RESULT, MANY
RESERVOIRS AND RIVERS ARE AT, OR ARE APPROACHING, CRITICALLY
LOW LEVELS.
FOR EXAMPLE, IN CALIFORNIA, ONE OF THE STATES MOST IMPACTED,
LOCALLY HEAVY MID-FEBRUARY AND EARLY MARCH PRECIPITATION EASED
THE LONG-TERM DROUGHT ACROSS SOUTHERN SECTIONS, PARTICULARLY
ALONG THE COAST. FOR THE STATE AS A WHOLE, THE RAINY SEASON
ATTAINED 87% OF NORMAL, BUT THE PERCENTAGES WERE MUCH LOWER IN
THE STATE'S MAJOR WATER SUPPLY AREAS IN THE NORTH. AT THE
TIME OF THIS SUMMARY, CALIFORNIA RESERVOIR STORAGE WAS 1.3
MILLION ACRE-FEET LESS THAN IT WAS A YEAR AGO. ELSEWHERE,
RESERVOIRS IN EASTERN OREGON, SOUTHERN IDAHO, AND NORTHERN
NEVADA ARE SEVERELY DEPLETED, AND MANDATORY WATER RESTRICTIONS
HAVE GONE INTO EFFECT AT SEVERAL LOCATIONS.
THE ABOVE CONDITIONS HAVE CAUSED THE FIRE SEASON IN THE WEST
TO RAPIDLY COMMENCE. THE PREDICTED FIRE SEVERITY HAS RISEN TO
DANGEROUSLY HIGH LEVELS FROM THE NORTHERN THIRD OF THE
INTERMOUNTAIN WEST AND ROCKIES SOUTHWARD INTO THE GREAT BASIN.
LAST YEAR, THE POTENTIAL FIRE DANGER WAS AT SIMILARLY HIGH
LEVELS, BUT LOW SUMMERTIME TEMPERATURES AND HIGH HUMIDITIES
KEPT THE NUMBER OF FIRES AND ACRES BURNT WELL BELOW NORMAL
ACROSS THE CONTIGUOUS U.S. SO FAR IN 1992, HOWEVER,
CONDITIONS HAVE NOT BEEN AS FAVORABLE. THIS YEAR'S WORST
WILDFIRE OUTBREAK, MOSTLY CAUSED BY LIGHTNING STRIKES, HAS
SCORCHED OVER 310,000 ACRES SINCE JULY 31 IN THE PACIFIC
NORTHWEST AND GREAT BASIN. FORTUNATELY, THE WEATHER BRIEFLY
IMPROVED DURING THE SECOND WEEK OF AUGUST, ALLOWING
FIREFIGHTERS TO CONTAIN NEARLY ALL OF THE FIRES. THE
FORECAST, HOWEVER, EXPECTS THE RECENT HEAT WAVE TO CONTINUE
ACROSS MUCH OF THE WEST DURING MID-AUGUST.
ELSEWHERE, LATE SPRING DRYNESS IN THE MIDWEST AND MID-ATLANTIC
RAISED FEARS OF DROUGHT-INDUCED CROP FAILURE. FORTUNATELY,
COOL JUNE WEATHER KEPT EVAPORATIVE DEMANDS LOW, AND ABUNDANT
JULY RAINS ELIMINATED MUCH OF THE DRYNESS. SIMILAR CONCERNS
AFFECTED THE PRAIRIE PROVINCES OF WESTERN CANADA, BUT THESE
WERE QUELLED BY AMPLE JUNE AND JULY RAINFALL. THE MAIN
CONCERN IN MANITOBA AND PARTS OF THE CENTRAL AND MIDWESTERN
U.S. IS THE PERSISTENTLY COOL WEATHER SINCE JUNE WHICH HAS
DELAYED PLANT DEVELOPMENT AND HAS LEFT CROPS VULNERABLE TO
FROST DAMAGE BEFORE MATURITY AND HARVEST.
THE SEASONAL OUTLOOK (AUGUST THROUGH OCTOBER) INDICATES ABOVE
NORMAL TEMPERATURES WEST OF THE ROCKIES AND SUBNORMAL
PRECIPITATION IN THE PACIFIC NORTHWEST. MEANWHILE,
UNSEASONABLY COOL WEATHER IS FORECAST FOR THE CENTRAL U.S. AND
THE NORTHEAST. ABOVE NORMAL PRECIPITATION IS PREDICTED FROM
THE SOUTHERN ROCKIES AND PLAINS NORTHEASTWARD ACROSS THE
MIDWEST INTO NORTHERN NEW ENGLAND.
SUBNORMAL STREAMFLOWS ARE EXPECTED TO CONTINUE ACROSS THE
NORTHWESTERN QUARTER OF THE COUNTRY DURING AUGUST. ABOVE
NORMAL STREAMFLOWS SHOULD PERSIST ACROSS SOUTHERN CALIFORNIA
AND MOST OF ARIZONA, AND FROM CENTRAL TEXAS NORTHWARD INTO THE
CENTRAL GREAT PLAINS AND MIDDLE MISSISSIPPI VALLEY EASTWARD
ACROSS THE LOWER OHIO VALLEY INTO SOUTHERN NEW ENGLAND.
THIS IS A SUMMARY OF CURRENT CONDITIONS, IMPACTS, AND OUTLOOKS
ISSUED BY THE NMC CLIMATE ANALYSIS CENTER WITH INPUT FROM
NUMEROUS FEDERAL, REGIONAL, AND STATE AGENCIES. A SUPPLEMENT
TO THIS ADVISORY WILL BE ISSUED IF CONDITIONS CONTINUE TO
DETERIORATE. GRAPHICS MAY BE AVAILABLE WITH FUTURE
ADVISORIES.
END - SENT W/OM23
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