National Weather Service New York, NY Watch Warning Advisory Definitions Page

Hazardous Weather Outlooks, Watches, Warnings and Advisories

Important Note: The criteria listed below apply to the service area of the National Weather Service (NWS) Forecast Office in Upton, NY.

Click to see NWS Eastern Region Winter Warning and Advisory Criteria

Outlook
Indicates the potential for significant weather events up to 7 days in advance with a forecaster confidence around 30%.

Watch
Indicates that conditions are favorable for the particular weather event in and near the Watch area, and which may pose a risk to life and property. Watches are issued up to 48 hours in advance with forecaster confidence around 50%.

Warning/Advisory
Indicates that a particular weather event is imminent or occurring. Advisories are issued if the weather event will lead to nuisance conditions, while Warnings are issued for significant weather events which will pose a risk to life and property. Warnings and Advisories are issued up to 48 hours in advance with forecaster confidence of at least 80%.

Note: Watches and Warnings issued for Severe Thunderstorms, Tornadoes, and Flash Flooding have much shorter lead times, on the order of hours for Watches or even minutes for Warnings.

Red Flag Warning
Issued to indicate that the combination of dry fuels and weather conditions will support extreme fire danger and/or fire behavior, including the potential for widespread new ignitions or control problems with existing fires.  Warning criteria typical for the spring and fall are winds sustained or frequently gusting above 25 mph, relative humidity less than 30%, and widespread rainfall less than 1/4 inch during the previous three or more days. In the summer, the rainfall criteria is extended to five or more days, as well as a Keetch-Byram Drought Index above 300 which indicates at least the top three inches of the ground are sufficiently dry. A Red Flag Warning may or may not be preceded by a Fire Weather Watch.

Hurricane Force Wind Warning
Issued when a non-tropical system is forecast to produce sustained winds or frequent gusts of 64 knots or greater.

Storm Warning
Issued for sustained winds or frequent gusts of 48 to 63 knots, not associated with a tropical system.

Gale Warning
Issued for sustained winds or frequent gusts of 34 to 47 knots, not associated with a tropical system.

Small Craft Advisory
Issued for sustained winds or frequent gusts of 25 to 33 knots and/or hazardous seas with waves of 5 feet or higher.

Special Marine Warning
Issued to convey information regarding hazardous convective activity or other short-term weather events occurring over the water or which may impact those on the water that are not covered by the current forecast.

Dense Fog Advisory
Issued when widespread fog is expected to reduce visibilitiy to 1 nautical mile or less.

Freezing Spray Advisory
Issued when freezing spray is expected to pose a significant hazard to marine vessels.

High Surf Advisory
Issued when expected high/rough surf poses a threat to life and/or property during the beach season ( typically late May through September).

Low Water Advisory
Issued when tidal levels are expected to be low enough to cause problems for shipping and other marine interests.

Tsunami Warning
Issued by the National Tsunami Warning Center under the ANCTSUAT1 and ANCTSUATE products. The TSUAT1 product is a tabular formatted product that contains technical details of the tsunami including location, magnitude and forecasted arrival time(s). The TSUATE product is a narrative styled product that will contain the same warning/watch information as the TSUAT1 product, but presented in a less technical style suitable for the general public

High Wind Warning
Issued when sustained winds of 40 mph or greater are forecast for 1 hour or longer, or wind gusts of 58 mph or greater for any duration.

Wind Advisory
Issued when sustained winds of 30 to 39 mph are forecast for 1 hour or longer, or wind gusts of 46-57 mph for any duration.

Excessive Heat Warning
Issued when heat index values are forecast to reach or exceed 105°F for at least 2 consecutive hours.

Heat Advisory
Issued when the heat index is forecast to reach 95F or greater for at least 2 consecutive days or 100 to 104F for any length of time.

Freeze Warning
Issued when overnight minimum temperatures are forecast to reach 32F or lower during the growing season. They are usually issued to highlight the first few freezes of the fall, or unusually late freezes in the spring.

Frost Advisory
Issued when conditions are favorable for frost development during the growing season due to overnight minimum temperatures falling between 33°F to 36°F.

Air Quality Alert
Issued by the NYSDEC (Department of Environmental Conservation), NJDEP (Department of Environmental Protection), and/or CTDEP when ground ozone concentrations and/or particulate matter are forecast to become unhealthy for sensitve groups of people(Air Quality Index greater than or equal to 100).

Dense Fog Advisory
Issued when widespread fog is expected to reduce visibilitiy to 1/4 mile or less.

Winter Storm Warning
Issued for a winter weather event in which there is more than one of the following: snow, sleet, and ice (freezing rain), and one of the warning criteria is met. The warning criteria for snow is 6 inches expected in a 12 hour period, or 8 inches expected in a 24 hour period. The warning criteria for ice is accumulations meeting or exceeding 1/2 inch.  A winter storm warning may also be issued for heavy snow combined with strong winds of 25-34 mph that will cause blowing and drifting of the snow. A warning may still be warranted if the event is expected to exceed advisory criteria, but fall just short of warning criteria and will significantly impact mass transit and/or utilities.

Blizzard Warning
Issued for sustained winds or frequent gusts greater than or equal to 35 mph accompanied by falling and/or blowing snow, frequently reducing visibility to less than 1/4 mile for three hours or more.

Ice Storm Warning
Issued when freezing rain is expected to produce ice accumulations of 1/2 inch or greater, or cause significant disruptions to travel or utilities.

Wind Chill Warning
Issued when wind chill values will reach -25°F or colder.

Winter Weather Advisory
Issued for a winter weather event in which there is more than one of the following: snow, sleet, and ice (freezing rain), and one of the advisory criteria is met but does not exceed warning criteria. In addition, a winter weather advisory will be issued for an all-snow event if the advisory criteria is met but does not exceed the warning criteria. The advisory criteria is 3 inches of snow and/or sleet expected in a 12 hour period, or a trace of ice accumulation.  An advisory may still be warranted if lesser accumulations will significantly impact mass transit and/or utilities.

Wind Chill Advisory
Issued when wind chill values will reach -15°F to -24°F.

Snow Squall Warning
Issued when there is expectation of an intense snow shower, which could produce a brief period of heavy snow, gusty winds, near zero visibility, and potential flash freeze conditions within the next hour.