A Blizzard Warning (SAME code: BZW) is an advisory issued by the National Weather Service of the United States which means sustained winds or frequent gusts of 35 mph / 15 m/s or greater with heavy snow is forecast for a period of 3 hours or more. A blizzard tends to reduce visibilities to 1/4 of a mile (400 m) or less. A Severe Blizzard Warning is a variation issued in some cases of winds above 45 mph / 20 m/s and temperatures below 10 °F/-12 °C. Most local weather offices will activate and broadcast the SAME alarm tone on relevant NOAA Weather Radio stations for both varieties of warning.
- National Warning below tree line - when winds are 40 kilometres/hr or greater with widespread reductions in visibility to 400 metres (1/4 mile) or less from blowing snow or blowing snow with falling snow for at least 4 hours.
- Northern (Arctic) Warning above tree line - same as National Warning but must last for at least 6 hours.
Example of a blizzard warning (US)
165 WWUS41 KOKX 012056 WSWOKX URGENT - WINTER WEATHER MESSAGE NATIONAL WEATHER SERVICE NEW YORK NY 356 PM EST WED JAN 1 2014 ...A COASTAL STORM WILL BRING THE POTENTIAL FOR HEAVY SNOW...STRONG WINDS AND DANGEROUSLY COLD WIND CHILLS THURSDAY EVENING THROUGH FRIDAY AFTERNOON... NYZ078>081-177-179-021000- /O.UPG.KOKX.WS.A.0005.140102T2300Z-140103T1800Z/ /O.NEW.KOKX.BZ.W.0001.140102T2300Z-140103T1800Z/ NORTHWESTERN SUFFOLK-NORTHEASTERN SUFFOLK-SOUTHWESTERN SUFFOLK- SOUTHEASTERN SUFFOLK-NORTHERN NASSAU-SOUTHERN NASSAU- 356 PM EST WED JAN 1 2014 ...BLIZZARD WARNING IN EFFECT FROM 6 PM THURSDAY TO 1 PM EST FRIDAY... THE NATIONAL WEATHER SERVICE IN NEW YORK HAS ISSUED A BLIZZARD WARNING...WHICH IS IN EFFECT FROM 6 PM THURSDAY TO 1 PM EST FRIDAY. THE WINTER STORM WATCH IS NO LONGER IN EFFECT. * LOCATIONS...LONG ISLAND INCLUDING NASSAU AND SUFFOLK COUNTIES. * HAZARD TYPES...SNOW AND BLOWING SNOW. * ACCUMULATIONS...UP TO AROUND 1 INCH OF SNOW IS FORECAST OVERNIGHT THROUGH THE THURSDAY MORNING RUSH HOUR. AN ADDITIONAL 7 TO 9 INCHES OF SNOW IS FORECAST THURSDAY EVENING THROUGH FRIDAY. TOTAL ACCUMULATIONS OF 8 TO 10 INCHES ARE FORECAST. * WINDS...NORTH 25 TO 35 MPH WITH GUSTS UP TO 45 MPH. * TEMPERATURES...IN THE LOWER 20S. * VISIBILITIES...ONE QUARTER MILE OR LESS. * TIMING...THE HEAVIEST SNOW AND THE STRONGEST WINDS WILL OCCUR THURSDAY NIGHT INTO FRIDAY. * IMPACTS...BLOWING AND DRIFTING SNOW WILL PRODUCE DANGEROUS TRAVEL CONDITIONS. WIND CHILLS FROM 5 DEGREES BELOW ZERO TO 5 DEGREES ABOVE ZERO WILL PRODUCE EXTREME COLD IMPACTS. PRECAUTIONARY/PREPAREDNESS ACTIONS... A BLIZZARD WARNING MEANS SEVERE WINTER WEATHER CONDITIONS ARE EXPECTED OR OCCURRING. FALLING AND BLOWING SNOW WITH STRONG WINDS AND POOR VISIBILITIES ARE LIKELY. THIS WILL LEAD TO WHITEOUT CONDITIONS...MAKING TRAVEL EXTREMELY DANGEROUS. DO NOT TRAVEL. IF YOU MUST TRAVEL...HAVE A WINTER SURVIVAL KIT WITH YOU. IF YOU GET STRANDED...STAY WITH YOUR VEHICLE. && $$
Example of a blizzard warning (Canada)
FPCN16 CWNT 071600 Warnings Hall Beach 12:41 PM EST Thursday 07 February 2013 Blizzard warning for Hall Beach continued Blizzard conditions today. This is a warning that blizzard conditions are imminent or occurring in these regions. Monitor weather conditions.. listen for updated statements. A strong storm system located over Davis Strait that produced blizzard conditions at Clyde River is weakening. Blizzard conditions are still affecting Hall Beach but as winds decrease today blizzard conditions will begin to improve at Hall Beach later this afternoon.