| ...WARNING... |
| Tornado Warning |
Tornado is indicated by radar or sighted by storm spotters. The warning will include where the tornado is and what towns will be in its path. |
| Severe Thunderstorm Warning |
Issued when a thunderstorm produces hail 3/4 of an inch or larger in diameter and/or winds which equal or exceed 58 mph. Severe thunderstorms can result in the loss of life and/or property. Information in this warning includes: where the storm is, what towns will be affected, and the primary threat associated with the storm. |
| Flash Flood Warning |
Issued to inform the public that flash flooding is imminent or occurring. |
| Tsunami Warning |
Issued by the ATWC when an earthquake greater than 7.0 but less than or equal to 7.5 on the Richter Scale occurs. The warning will cover an area within 350 KM from epicenter
Issued by the ATWC when an earthquake greater than 7.5 but less than 7.9 on the Richter Scale occurs. The warning will cover an area within 1000 KM from the epicenter |
Issued by the ATWC when an earthquake greater than 7.9 or higher on the Richter Scale occurs. The warning will cover an area within 3 hours wave travel time
| Storm Warning (Marine) |
Winds of 48 knots or more, either forecast or occurring. |
| Heavy Snow Warning |
Mountains >7000 feet -- 12+ in/12 hrs or 18+ in/24 hrs.
Mountains between 3000-7000 feet -- 8+ in/12 hrs or 12+ in/24 hrs.
Mountains <3000 feet -- 5+ in/12 hrs or 7+ in/24 hrs.>
Also, for the first Autumn or Winter snow, or for an unusually late Spring snow: 4+ in/12 hrs or 6+ in/24 hrs.
Snow accumulations where it is rare. |
| Winter Storm Warning |
Generally issued for the 1st period of the forecast when more than one hazardous weather events are occurring or are expected to occur. If only one is occurring or is expected to occur, the warning shall be issued as an event-specific warning. Issued by each NWSO. |
| Coastal Flood Warning |
Coastal flooding is occurring or is imminent |
| High Surf Warning |
Significant Wave Height of 20 feet or greater at the coast. High Surf Warnings should be issued when an especially
heightened threat to life and/or property exists or is expected. |
| Flood Warning |
Issued when flooding is expected to occur more than 6 hours after the causative event (e.g., heavy rain, snow melt or reservoir releases). Flood warnings are issued for forecast points, areas along rivers and streams, and for counties or portions of counties. |
| High Wind Warning |
Warning (next 36 hours)
Sustained winds >= 35 knots (>= 40 mph)
and/or gusts (for elevations of 900 feet and below) >= 50 knots (>= 58 mph )
and/or gusts (for elevations between 900-2500 feet) >= 61 knots (>= 70 mph )
Note: High wind watches and warnings will not be issued for winds above 2500 feet. |
| Excessive Heat Warning |
Heat Index at least 115 for 3 hours or more, with minimum nighttime heat index at or above 80 or based on the heat health watch warning system. [Heat Index Chart] |
| Red Flag Warning |
A "Red Flag Warning" is issued if Red Flag conditions are imminet or ongoing. Warnings are usually issued within 24 hours of the onset of the event.
For specific criteria see the Red Flag Guidance/Verification Matrix |
| Freeze Warning |
For the inner urban core of the San Francisco Bay Area. Essentially, the inner urban core comprises zone 006 (San Francisco), zone 508 (San Francisco Bay Shoreline) and the northern portion of zone 513 (Santa Clara Valley, Including San Jose).
- Any time minimum temperature is expected to fall below 32 F for a minimum of two consecutive hours at two or more locatons within the zone.
For the remainder of the CWA except excluded outlying portions of Monterey and San Benito Counties. Freeze warnings will never be issued for outlying portions of Monterey and San Benito counties.
- Any time minimum temperature is expected to be <= 28 F for a minimum of two consecutive hours at two or more locations within the zone.
Note for mountain zones: Freeze Warnings are typically not issued for mountain zones. However, an exception should be made for the North Bay Mountains zone (zone 507) as there are several valleys in this zone below 1000 feet with agricultural interests (wineries, etc.)
|
| Gale Warning (Marine) |
Winds of 34 to 47 knots, either forecast or occurring. |
| Special Marine Warning |
Issued to provide notification of short duration marine hazards such as waterspouts, thunderstorms, or hail. |
| Airport Weather Warning |
1) When surface winds, sustained and/or gusts, reach 35 knots or greater.
2) When lightning is within 5 miles of the airport.
3) Thunderstorms at the airport with = or > 1/2 inch hail (pea size). |
| ...WATCH... |
| Tornado Watch |
Conditions are favorable for the development of tornadoes in and close to the watch area. Watches are usually in effect for several hours, with 6 hours being the most common. |
| Severe Thunderstorm Watch |
Conditions are favorable for the development of severe thunderstorms in and close to the watch area. Watches are usually in effect for several hours, with 6 hours being the most common. |
| Flash Flood Watch |
- Meteorological, soil, or hydrologic conditions indicate flash flooding is possible or,
- The effective time of a pre-existing flash flood watch changes or,
- The geographical area covered by a pre-existing flash flood watch increases or,
- A dam could fail and threaten life and property, but the threat does not appear imminent.
|
| Tsunami Watch |
Issued by the ATWC when an earthquake greater than 7.8 on the Richter Scale occurs. The watch will cover an area within 3-6 hours tsunami wave travel time.
|
| Coastal Flood Watch |
Alerts the public of possible coastal flooding within 12 to 36 hours. |
| Flood Watch |
Issued to inform the public that current and developing hydro conditions are such that there is a threat of flash flooding, but the occurrence is neither certain nor imminent. |
| Winter Storm Watch |
Issued for late 1st through 4th period for possible dangerous winter weather. Changed to warning as event becomes more certain. Issued by each NWSO. |
| High Wind Watch |
High Wind Watch (12-48 hours)
Sustained winds >= 35 knots (>= 40 mph)
and/or gusts (for elevations of 900 feet and below) >= 50 knots (>= 58 mph )
and/or gusts (for elevations between 900-2500 feet) >= 61 knots (>= 70 mph )
Note: High wind watches and warnings will not be issued for winds above 2500 feet. |
| Excessive Heat Watch |
Conditions favorable for an excessive heat event to meet/exceed heat warning criteria in the next 12 to 48 hours. [Heat Index Chart] |
| Freeze Watch |
Conditions are favorable for a freeze event to meet or exceed Freeze Warning criteria in the next 12 to 48 hours. |
| Fire Weather Watch |
A "Fire Weather Watch" is issued when there is reasonable confidence the a Red Flag event will occur. Watches are issued 12-48 hours prior to the onset of on event, but may be issued within the first 12 hours for the occurrence of dry lightning. Generally Watches are not issued more than 72 hours before an event. |
| ...ADVISORY... |
| Winter Weather Advisory |
Winter weather significant to the public, but not enough of a threat to life or property to warrant a warning. Examples of what may be issued: snow, freezing rain, blowing/drifting snow, etc. If only one is expected, the advisory should be issued as event specific. Issued by each NWS Forecast Office. |
| Heat Advisory |
Heat index of 105 daytime and/or 80 nighttime. [Heat Index Chart] |
| Snow Advisory |
Mountains >7000 feet -- 7-11 in/12 hrs or 8-17 in/24 hrs.
Mountains above 3000-7000 feet -- 4-7 in/12 hrs or 6-11 in/24 hrs.
Mountains <3000 feet -- 2-4 in/12 hrs or 4-6 in/24 hrs. >
Snow accumulations where it is rare.
Also, for the first Autumn or Winter snow, or for an unusually late Spring snow:
Mountains above 3000-7000 feet -- 2-4 in/12 hrs or 4-6 in/24 hrs.
Mountains <3000 feet -- 1-2 in/12 hrs or 2-4 in/24 hrs. >
Snow accumulations where it is rare. |
| Small Craft Advisory (Marine) |
Winds 21 to 33 knots or combined seas expected or occurring that are considered potentially hazardous to small craft.
Note: There is no legal definition of "small craft" |
| High Surf Advisory |
Combined seas of 15 feet or greater. Criteria varies slightly with wave period. |
| Dense Fog Advisory |
Visibilities must be <1/4 mile for all fog/restricted visibility products. The difference between a watch/warning and an advisory is that a watch/warning event poses a threat to life and property while an advisory is for conditions that are mostly an inconvenience. The restricting agent may be fog, dust, blowing sand, volcanic ask, smoke, etc. The restricting agent will be in the name of the product, i.e. Fog Advisory, Dust Storm Warning, etc... |
| Wind Advisory |
Sustained winds 30 to 34 knots (35 to 39 mph) for elevations at or below 2500 feet.
and/or gusts 39 to 49 knots (45 to 57 mph) for elevations at or below 2500 feet. |
| Frost Advisory |
For the inner urban core of the San Francisco Bay Area. Essentially, the inner urban core comprises zone 006 (San Francisco), zone 508 (San Francisco Bay Shoreline) and the northern portion of zone 513 (Santa Clara Valley, Including San Jose).
- Any time when the minimum temperature is expected to be in the 32-35 F range for a minimum of two consecutive hours at two or more locations within the zone.
For the remainder of the CWA:
- First two times during the cool season when the minimum temperature is expected to be in the 29-35 F range for a minimum of two consecutive hours at two or more locations within the zone. And, any time these criteria are met after April 1st.
Note for mountain zones: Frost Advisories are typically not issued for mountain zones. However, an exception should be made for the North Bay Mountains zone (zone 507) as there are several valleys in this zone below 1000 feet with agricultural interests (wineries, etc.)
|
| Urban/Small Stream Flood Advisory |
Flooding of streets, underpasses, low lying areas, or storm drains. This type of flooding is mainly an inconvenience and is generally considered not to be life threatening. |
| Coastal Flood Advisory |
Coastal flooding is occurring, imminent or highly likely in first 12 hours. |
| ...STATEMENT... |
| Flash Flood Statement |
Used as a follow-up to Flash Flood Warnings and Watches. The statement will contain the latest information on the event. |
| Severe Weather Statement |
Issued when the forecaster wants to follow up a warning with important information on the progress of severe weather elements or to end the warning. |
| Marine Weather Statement |
A product to inform mariners of significant or potentially hazardous conditions not otherwise covered in existing warnings or forecasts. Also issued to provide follow-up information on Special Marine Warnings (expire, cancel or updates). |
| Marine Weather Message |
Coming Soon! |
| Drought Statement |
Coming Soon! |
| Coastal Hazard Message |
Used to update, extend, cancel, or expire a Coastal Flood Watch, Warning, or Advisory. or
Used to update, extend, cancel, or expire "High Surf Advisories. |
| Special Weather Statement |
Special Weather Statements (SPS) provide the public with information concerning ongoing or imminent weather hazards or winter weather/non precipitation outlook information. |
| Flood Statement |
Used as a follow-up to Flood Warnings, Watches and advisories. Also used to issue Urban and Small Stream Flood Advisories. |
| ...OUTLOOK... |
| Hazardous Weather Outlook |
issued to highlight possible hazardous/severe weather threats from days 1 through 7 associated with convective weather, winter weather, fire weather, floods, high winds, and marine hazards (including high surf and coastal flooding), etc. Weather threats that would be included in a hazardous weather outlook are those that would be expected to reach the level that poses a threat to live and/or property and typically requires the issuance of an outlook, watch, or warning. Advisories or the potential thereof are also mentioned in the HWO to communicate to the public that nuisance type weather can be expected which may be dangerous if caution is not taken. |
| Hydrologic Outlook |
Issued if precipitation forecasts or snow melt potential indicate the possibility of flooding beyond 36 hours. This product may also be used to provide additional hydrologic information such as seasonal water supply and dry weather conditions. |
| Winter Weather Outlook |
Issued as a "heads up" for the possibility of significant winter weather in the 4th period or extended range. |
| High Wind Outlook |
Issued as a "heads up" for the possibility of significant winds in 4th period or extended range. |
| Freeze Outlook |
Potential for a freeze event to exceed Freeze Warning criteria in the next 3 to 7 days. |
| OTHER |
| Short Term Forecast |
A short term forecast designed to give specific, detailed forecast information for the next 1 to 6 hours on a county-by-county basis. Both routine and near-severe information are contained in these forecasts which are routinely issued several times per day, and more often during busy weather periods. |
| Local Storm Report |
Used to distribute severe weather reports to the media, emergency managers, and other NWS offices. It is issued as reports are received, and may also be issued as a collection of all reports received after an event is over. Delayed reports are disseminated after an event is over as well. |
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