Weather services issue a gale warning for maritime locations currently or imminently experiencing winds of gale force on the Beaufort scale. Gale warnings (and gale watches) allow mariners to take precautionary actions to ensure their safety at sea or to seek safe anchorage and ride out the storm on land. Though usually associated with deep low-pressure areas, winds strong enough to catalyze a gale warning can occur in other conditions too, including from anticyclones, or high-pressure systems, in the continental interior.
In the United States, the National Weather Service issues gale warnings for marine areas (oceans, sounds, estuaries, and the Great Lakes) experiencing, or about to experience, winds within the range of 34 knots (63 km/h; 39 mph) to 47 knots (87 km/h; 54 mph). In United States maritime warning flag systems, two red pennants indicate a gale warning; the use of one such flag denotes a small craft advisory.
The National Weather Service issues a storm warning for higher winds of 48 knots (89 km/h; 55 mph) to 63 knots (117 km/h; 72 mph) at sea. In the event of a tropical cyclone, however, a tropical storm warning replaces the gale warning or storm warning. The storm-warning maritime flag also replaces the gale-warning flag, regardless of the strength or weakness of the tropical storm.
The National Weather Service issues a similar high wind warning (Specific Area Message Encoding code: HWW) for high winds on land. The criteria vary from place to place; however, in most cases, the warning applies to winds of 40 miles per hour (64 km/h) to 57 miles per hour (92 km/h) for at least 1 hour; or any gusts of 58 miles per hour (93 km/h) to 73 miles per hour (117 km/h) on land unless a tropical storm warning, blizzard warning, winter storm warning, severe thunderstorm warning, or dust storm warning covers the phenomenon.
In the United Kingdom, the Meteorological Office issues gale warnings, and radio broadcasts them four times a day at fixed times on 198 kHz in the Shipping Forecast, part of the broadcast output of BBC Radio 4. If a considerable time will intervene before the next Shipping Forecast, forecasters may issue an extra gale warning, read between programmes. The Meteorological Office issues warnings for sea areas surrounding the United Kingdom for all predictions of winds of Beaufort scale Force 8 or greater, the forecasts extending as far north as Iceland and as far south as southern Spain.
Met Éireann, the Republic of Ireland meteorological office, issues an area forecast for the Irish Sea and warnings for sea areas around Ireland with headlands of Ireland (e.g. Fair Head, Malin Head, Mizen Head, Carnsore Point) defining stretches of coast.
Example of Gale Warning
URGENT - MARINE WEATHER MESSAGE NATIONAL WEATHER SERVICE NORTHERN INDIANA 901 PM EDT WED OCT 29 2014 LMZ043-046-300915- /O.CON.KIWX.GL.W.0014.141031T1200Z-141101T0900Z/ NEW BUFFALO MI TO ST JOSEPH MI-MICHIGAN CITY IN TO NEW BUFFALO MI- 901 PM EDT WED OCT 29 2014 ...GALE WARNING REMAINS IN EFFECT FROM 8 AM FRIDAY TO 5 AM EDT SATURDAY... * WINDS...NORTHWEST 15 TO 25 KNOTS WITH GUSTS TO 30 KNOTS BY DAYBREAK FRIDAY...VEERING NORTH TO 35 KNOT GALES WITH GUSTS TO 45 KNOT GALES FRIDAY. NORTH WINDS DIMINISHING TO 20 TO 30 KNOTS WITH GUSTS TO 35 KNOT GALES LATE FRIDAY NIGHT. * WAVES..5 TO 8 FEET LATE THURSDAY NIGHT...BUILDING TO 14 TO 20 FEET FRIDAY...SUBSIDING TO 8 TO 12 FEET LATE FRIDAY NIGHT. PRECAUTIONARY/PREPAREDNESS ACTIONS... A GALE WARNING MEANS WINDS OF 34 TO 47 KNOTS ARE IMMINENT OR OCCURRING. OPERATING A VESSEL IN GALE CONDITIONS REQUIRES EXPERIENCE AND PROPERLY EQUIPPED VESSELS. IT IS HIGHLY RECOMMENDED THAT MARINERS WITHOUT THE PROPER EXPERIENCE SEEK SAFE HARBOR PRIOR TO THE ONSET OF GALE CONDITIONS. && $$ STAY TUNED TO NOAA WEATHER RADIO FOR FURTHER DETAILS OR UPDATES...OR CHECK OUR WEB SITE AT WEATHER.GOV/IWX/?N=MARINE