Non-Precipitation Weather Advisory(NPW, WWUS74)
Non-precipitation hazard advisories are issued when existing or imminent significant events cover part or all of the forecast area. Excessive heat, obstruction to vision situations, and sustained winds of less than 40 miles an hour are covered by advisories.
Advisories are issued for the the 0-12 hour time frame. They can be extended to 24 hours if the event is expected to continue. Advisories are reissued whenever there is a change to the timing, areal extent, or expected conditions. The advisory provides details about the following...
- Area and time affected,
- Potential wind speeds and heat index, worst conditions, general impact, etc.,
- Timing of events beginning, ending, peaking, weakening,
- Reasons for the advisory,
- Advisory definition, and
- Simple precautions/calls to action.
Large lakes are a concern because of the recreational uses and the lack of understanding by many people of the increased wind speeds over water versus adjoining land. Wind over open water is normally stronger than reported over land. Because most lakes are narrow and long, the danger of high waves increases when the wind is parallel to the long axis of the lake. Strong wind will be handled in one of two way; wind advisories may be issued for lakes and not the surrounding land areas or the phrase "CAUTION IS ADVISED ON AREA LAKES" will be added to the first period of your local forecast.
Whenever advisories are in effect, special weather statements will be issued to include the current advisory information, updated weather details, and call to action statements.
Example
FTWNPWFTW
TTAAOO KFTW 221800
TXZ091>093-100>104-115>120-129>134-141>146-156>160-160200-
URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE FORT WORTH TX
1100 AM CST SAT DEC 21 1991
THE NATIONAL WEATHER SERVICE HAS ISSUED A DENSE FOG ADVISORY FOR A LARGE
PART OF NORTH CENTRAL AND NORTHEAST TEXAS. THE ADVISORY AREA IS SOUTH OF
A EASTLAND...CENTERVILLE LINE. THE CITIES OF WACO...TEMPLE...AND KILLEEN
ARE INCLUDED.
LATE THIS EVENING A LOW LEVEL TEMPERATURE INVERSION WAS ACTING TO TRAP
MOISTURE NEAR THE SURFACE AHEAD OF A WARM FRONT OVER SOUTH TEXAS. THIS
SITUATION WAS RESULTING IN WIDESPREAD DENSE FOG THAT WILL LIKELY
CONTINUE THROUGHOUT MUCH OF TONIGHT. VISIBILITIES IN SOME AREAS MAY BE
REDUCED TO LESS THAN 1/4 MILE.
YOU SHOULD EXERCISE EXTREME CAUTION...AS VISIBILITIES CAN QUICKLY DROP
TO NEAR ZERO IN SOME LOCALIZED AREAS. REMEMBER TO USE LOW BEAM
HEADLIGHTS AND TO REDUCE SPEEDS IN ACCORDANCE WITH REDUCED VISIBILITIES.
STAY TUNED TO NOAA WEATHER RADIO OR YOUR FAVORITE NEWS SOURCE FOR FURTHER
STATEMENTS. |
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