A hurricane force wind warning is a warning issued by the National Weather Service of the United States when sustained winds or frequent gusts of 64 knots (118 km/h, 74 mph) or greater are either being observed or are predicted to occur. The winds must not be directly associated with a tropical cyclone, or a hurricane warning will be issued. If winds are lighter than 64 knots, a storm warning or gale warning will be issued. In US maritime warning flag systems, two red square flags with a black square taking up the middle ninth of each flag is used to indicate a hurricane force wind warning (the use of one such flag denotes a storm warning or a tropical storm warning).
This section possibly contains original research. (August 2017)
URGENT - MARINE WEATHER MESSAGE NATIONAL WEATHER SERVICE PORTLAND OR 249 AM PDT MON MAR 12 2012 PZZ255-275-121800- /O.CON.KPQR.HF.W.0002.000000T0000Z-120313T0100Z/ COASTAL WATERS FROM CASCADE HEAD TO FLORENCE OR OUT 10 NM- WATERS FROM CASCADE HEAD TO FLORENCE OR FROM 10 TO 60 NM- 249 AM PDT MON MAR 12 2012 ...HURRICANE FORCE WIND WARNING REMAINS IN EFFECT UNTIL 6 PM PDT THIS EVENING... A HURRICANE FORCE WIND WARNING REMAINS IN EFFECT UNTIL 6 PM PDT THIS EVENING. * WINDS...SOUTH WIND 40 TO 50 KT WITH GUSTS TO 70 KT EXPECTED TO PEAK MONDAY MORNING OVER THE OUTER WATERS...WITH LOCAL GUSTS TO 75 KT POSSIBLE OVER THE INNER WATERS MONDAY LATE MORNING AND EARLY AFTERNOON. * SEAS....COMBINED SEAS WILL REACH 28 TO 30 FEET EARLY MONDAY MORNING...POSSIBLY HIGHER...THEN EASE TO AROUND 20 FEET BY EARLY MONDAY EVENING. SEAS WILL BE QUITE CHOPPY WITH A HIGH SOUTH TO SOUTHWEST WIND WAVE COMPONENT...AND A WEST LONGER PERIOD SWELL COMPONENT. PRECAUTIONARY/PREPAREDNESS ACTIONS... A HURRICANE FORCE WIND WARNING MEANS WINDS OF 64 KNOTS OR GREATER ARE IMMINENT OR OCCURRING. ALL VESSELS SHOULD REMAIN IN PORT...OR TAKE SHELTER AS SOON AS POSSIBLE...UNTIL WINDS AND WAVES SUBSIDE.
- National Weather Service. "Hurricane Force Wind Warning". Glossary - National Weather Service. Retrieved 21 July 2011.