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-------- Original Message --------971 NOUS41 KWBC 281358
PNSWSHTECHNICAL IMPLEMENTATION NOTICE 02-30A NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC 1000 AM EDT THU SEP 28 2006
TO: FAMILY OF SERVICES /FOS/ SUBSCRIBERS...NOAA WEATHER WIRE SERVICE /NWWS/ SUBSCRIBERS...EMERGENCY MANAGERS WEATHER INFORMATION NETWORK /EMWIN/ SUBSCRIBERS... OTHER NATIONAL WEATHER SERVICE /NWS/ CUSTOMERS OF AVIATION DATA AND FORECASTS...NWS EMPLOYEES FROM: MIKE CAMPBELL CHIEF...OBSERVING SERVICES DIVISION SUBJECT: AUTOMATED SURFACE OBSERVING SYSTEM WIND SENSOR REPLACEMENT. THE FOLLOWING CHANGES HAVE NO DIRECT IMPACT ON NOAA WEATHER WIRE SERVICE SUBSCRIBERS THE AUTOMATED SURFACE OBSERVING SYSTEM /ASOS/ PRODUCT IMPROVEMENT PROGRAM WILL SOON DEPLOY A REPLACEMENT WIND SENSOR. THE NEW SENSOR WILL REPORT WIND INFORMATION USING THE 3-SECOND WORLD METEOROLOGICAL ORGANIZATION /WMO/ GUST STANDARD. THE CURRENT ASOS WIND SENSOR /BELFORT 2000 / USES ROTATING CUPS TO MEASURE WIND SPEED AND A VANE TO MEASURE WIND DIRECTION. OVER A 2-MINUTE PERIOD...ASOS USES TWENTY-FOUR 5-SECOND AVERAGES TO DETERMINE THE 2-MINUTE AVERAGE WIND SPEED AND DIRECTION. EVERY MINUTE ASOS STORES THE HIGHEST 5-SECOND AVERAGE SPEED FOR THE PAST MINUTE... ALONG WITH ITS DIRECTION... IN THE 12-HOUR ARCHIVE FOR ADDITIONAL PROCESSING. THIS HIGHEST SPEED VALUE IS USED TO DETERMINE IF A GUST AND/OR A PEAK WIND REMARK WILL BE REPORTED. THE NEW ASOS WIND SENSOR /VAISALA 425NWS / IS A SONIC ANEMOMETER. IT HAS NO MOVING PARTS AND WILL OPERATE BETTER IN WINTER WEATHER CONDITIONS. AS WITH THE BELFORT SENSOR...OVER A 2-MINUTE PERIOD...ASOS USES TWENTY-FOUR 5-SECOND AVERAGES TO DETERMINE THE 2-MINUTE AVERAGE WIND SPEED AND DIRECTION. BUT THE HIGHEST 3-SECOND RUNNING AVERAGE SPEED IS STORED FOR GUST AND PEAK WIND PROCESSING. WHILE THERE WILL BE LITTLE DIFFERENCE IN 2-MINUTE AVERAGE WIND SPEED AND DIRECTION REPORTING...THE CHANGES IN GUST AND PEAK WIND REPORTING MAY BE SIGNIFICANT. WE CAN EXPECT TO SEE MORE GUSTS AND PEAK WINDS REPORTED WITH THE NEW SENSOR. THE MASS OF THE MOVING PARTS IN EXISTING SENSORS LIMITS RESPONSIVENESS. THE NEW SENSOR WILL BE MORE RESPONSIVE TO SHORT TERM GUSTS. THE FOLLOWING ASOS LOCATIONS HAVE OR WILL TRANSITION TO THE IFW CONFIGURATION ON THE INDICATED DATES:
HTL HOUGHTON LAKE ASOS SEPTEMBER 29, 2006IF YOU HAVE ANY QUESTIONS ABOUT THIS CHANGE...PLEASE CONTACT ONE OF THE FOLLOWING INDIVIDUALS AT NWS HEADQUARTERS: JAMES HEIL SURFACE OBSERVATIONS FOCAL POINT PHONE: 301-713-1792 X140 E-MAIL: JAMES.HEIL@xxxxxxxx OR RICHARD AHLBERG ASOS PLANNED PRODUCT IMPROVEMENT PROGRAM MANAGER PHONE: 301-713-1975 X160 E-MAIL: RICHARD.AHLBERG@xxxxxxxx. THIS AND OTHER NWS TECHNICAL IMPLEMENTATION NOTICES ARE AVAILABLE ON THE INTERNET AT /USE LOWER CASE/: HTTP://WWW.NWS.NOAA.GOV/OM/NOTIF.HTM END $$ NNNN
-- Linda Miller - lmiller@xxxxxxxxxxxxxxxx Community Services, Unidata University Corporation for Atmospheric Research P.O. Box 3000 Boulder, CO 80307-3000303-497-8646 fax: 303-497-8690
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