What Is a Special Weather Statement? In Plain Words

The purpose, in the supplement’s own words

The NWS Eastern Region supplement to National Weather Service Instruction 10-517, the Multi-Purpose Weather Products Specification, gives the Special Weather Statement (product category SPS) this purpose:

“The SPS is designed to alert customers to a short term hazardous weather threat, occurring through the first period or within 12 hours of the product issuance, which may require a heightened level of awareness or action.”

In plain words: it is a short-term heads-up about a hazardous weather threat, and the point of it is that you may need a heightened level of awareness or action.

The same supplement says the SPS will be accessible via Weather Forecast Office internet pages, similar to other watch, warning, and advisory products, and that it should also be broadcast on NOAA Weather Radio All Hazards (NWR).

Examples — one region’s list, not a national rule

The Eastern Region supplement, in a section about including latitude and longitude information in SPS products, gives this example list. The supplement’s own words are that the examples “include, but are not limited to” these:

• Heavy snow bands during a winter storm event
• Lake-effect snow bands that briefly reduce visibility
• Heavy rainfall that is not expected to cause flooding
• Thunderstorm winds of 40 to 57 miles per hour (sustained or in gusts)
• Hail less than one inch in diameter
• Frequent to continuous lightning
• Funnel clouds or cold air funnels
• Dense Valley Fog

Read that list as what it is: examples named in an Eastern Region supplement, under a heading about when offices in that region should add location information. It is not printed here as a nationwide list of criteria, and the supplement does not present it as one.

For storms that are not severe

An NWS Louisville page about changes to Severe Thunderstorm Warnings and Special Weather Statements says, in its own words: “SPSs are issued for storms that are not severe but may still cause negative societal impact.”

That page also says Special Weather Statements will be formatted in a similar way as Severe, Tornado, and Flash Flood Warnings: the SPS product will use a bullet format and include succinct “HAZARD”, “SOURCE”, and “IMPACT” sections, along with tags at the bottom of the product for expected hail size and wind gust speeds.

And it says NWS offices that have issued Significant Weather Advisories as SPS products will no longer do so, and that what had formerly been Significant Weather Advisories will now use the same format as all other SPSs.

How it differs from a Watch, a Warning, and an Advisory

The NWS “Watch Warning Advisory Explained” page defines the other three this way:

• Warning: A warning is issued when a hazardous weather or hydrologic event is occurring, imminent or likely. A warning means weather conditions pose a threat to life or property. People in the path of the storm need to take protective action.
• Advisory: An advisory is issued when a hazardous weather or hydrologic event is occurring, imminent or likely. Advisories are for less serious conditions than warnings, that cause significant inconvenience and if caution is not exercised, could lead to situations that may threaten life or property.
• Watch: A watch is used when the risk of a hazardous weather or hydrologic event has increased significantly, but its occurrence, location or timing is still uncertain. It is intended to provide enough lead time so those who need to set their plans in motion can do so. A watch means that hazardous weather is possible.

That page does not define the Special Weather Statement itself. The Statement is the separate product above: a short-term alert about a hazardous weather threat that may require a heightened level of awareness or action.

The NWS hazard simplification page, “Going Forward,” adds this about where the name itself is headed: it lists, as a benefit of the change, “Alert Clarity: Removes the most confusing terms (Advisory & Special Weather Statement) from the NWS alerting system,” and it says Special Weather Statements (SPS) will align with all other alerts by using the simplified bullet format. It also says the change creates an alerting system with only two primary terms to learn and explain — Watch and Warning — where the hazard is either possible or happening.

Its place in the national CAP list

The NWS Common Alert Protocol (CAP) Messages list carries the product as code SPS, name Special Weather Statement, with these initial issuance parameters: Urgency “Expected”, Severity “Moderate”, Certainty “Observed”, and Response Type “Execute”. The list itself notes that urgency, severity, certainty, and response may change with updates to the product.

Why there is no criteria list on this page

Unlike a Watch, a Warning, or an Advisory, the Special Weather Statement is not defined in the sources below by a set of nationwide trigger numbers. The Eastern Region supplement defines it by a broad purpose and an example list that is explicitly not limited to the items named.

So if you see a Special Weather Statement for your area, read the statement itself: it names the threat, the area, and the time period for where you live. The alert in effect where you live, and any numbers in it, come from your local National Weather Service Forecast Office.