Issued by NWS Cleveland, OH
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NOUS41 KCLE 201100
PNSCLE
OHZ003-006>014-017>023-027>033-036>038-047-089-211200-
PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CLEVELAND OHIO
600 AM EST FRI NOV 20 2009
...OHIO WINTER SAFETY WEEK 2009: NOVEMBER 15TH THROUGH NOVEMBER 21ST...
THE NATIONAL WEATHER SERVICE WILL FEATURE A DIFFERENT EDUCATIONAL
TOPIC EACH WEEK DAY DURING SAFETY WEEK. TODAYS TOPIC:
THE NEW WIND CHILL FORMULA.
THE NATIONAL WEATHER SERVICE AND METEOROLOGICAL SERVICES OF CANADA
HAVE DESIGN A WIND CHILL TEMPERATURE INDEX, DESIGNED TO CALCULATE
A MORE ACCURATE READING OF HOW THE COLD AIR FEELS ON THE HUMAN SKIN.
SINCE 1945, THE UNITED STATES AND CANADA HAVE USED AN INDEX,
WHICH RELIED ON OBSERVED WINDS 33 FEET ABOVE THE GROUND, AND
FOCUSED ON HOW FAST THE COLD TEMPERATURES COMBINED WITH WINDS
MADE WATER FREEZE. THE NEW INDEX ACCOUNTS FOR THE WIND EFFECTS AT
FACE LEVEL, AND A BETTER CALCULATION FOR BODY HEAT LOSS. FOR
EXAMPLE, UNDER THE OLD INDEX SYSTEM, A TEMPERATURE OF 20 DEGREES,
WITH A 15 MPH WIND, TRANSLATED INTO A READING OF FIVE DEGREES
BELOW ZERO. THE NEW INDEX CALCULATION WOULD TRANSLATE THE SAME
CONDITIONS TO SIX DEGREES ABOVE ZERO.
THE NEW INDEX IS BASED ON:
- WIND SPEED CALCULATED AT THE AVERAGE HEIGHT OF THE
HUMAN FACE, ABOUT FIVE FEET (THE HUMAN FACE IS MOST
OFTEN EXPOSED TO THE COLD).
- UPDATED HEAT TRANSFER THEORY, WHICH FACTORS HEAT LOSS
FROM THE BODY TO ITS SURROUNDINGS DURING COLD, WINDY
DAYS.
- A CONSISTENT STANDARD FOR SKIN TISSUE RESISTENCE.
- CLEAR NIGHT SKY CONDITIONS.
- A LOWERED CALM WIND THRESHOLD FROM FOUR MILES TO THREE
MILES.
TO OBTAIN MORE INFORMATION ON THE WIND CHILL CHANGE, VIEW THE WEB
SITE HTTP://WWW.NWS.NOAA.GOV/OM/WINTER/INDEX.SHTML.
GARNET
