Storm Prediction Center Day 4-8 Severe Weather Outlook Page (2024)

FAQs

What are the 5 levels of severe weather? ›

Those levels from 1 to 5 respectively are MARGINAL, SLIGHT, ENHANCED, MODERATE, and HIGH. An area under a MARGINAL risk for severe weather will feature a threat of isolated severe weather.

A 2% risk is often associated with marginal or slight risk days, indicating isolated severe storms are possible, with tornadoes being a secondary threat behind other severe weather, like hail or damaging winds.

Convective Outlook Issuance Times

Each Day 1 Convective Outlook is valid from the start of issuance (except for the 0600 UTC issuance which begins at 1200 UTC that day) through 1200 UTC the following day (except for the 0100 UTC issuance which is valid through that day).

Categorical Convective Outlooks

The traditional Convective Outlook is a categorical forecast that specifies the perceived level of threat via the descriptive wording: Slight Risk, Moderate Risk, and High Risk.

Except for heat-related fatalities, more deaths occur from flooding than any other weather-related hazard.

Threat: A low threat to life and property. Minimum Action: Preparations should be made for a low likelihood (or a 5 to 14% probability) of tornadoes; scattered tornadoes of F0 to F1 intensity possible. Potential Impact: The potential for scattered locations to experience minor to moderate tornado damage (see below).

There has never been an (E)F-6 tornado recorded, but they're technically not impossible. An F-6 tornado would need to reach wind speeds beyond 318 mph; however, the highest wind speeds ever recorded on Earth were 302 mph.

Today's tornado probabilities

If a hatched area is included in the image, which is only done with probabilities of 10 percent or higher, strong tornadoes are more of a concern than normal. The following tornado probabilities correspond to each SPC storm risk category.

No matter what type of manufactured home you live in, it is not a safe place to take shelter during a severe weath- er event. MOVE TO A SAFER STRUCTURE. Single family homes are safer, but not completely safe.

Lightning often strikes outside the area of heavy rain and may occur as far as 10 miles (16 kilometers) from any rainfall. Heat lightning is actually lightning from a thunderstorm too far away for thunder to be heard. You are in danger from lightning if you can hear thunder.

Has there ever been a day 3 moderate risk? ›

Day 3 moderate risks are quite rare; these have been issued only twenty times since the product became operational (most recently for March 22, 2022). Day 3 high risks are never issued and the operational standards do not allow for such.

The SPC is located in Norman, Oklahoma at the National Weather Center, which is on the campus of the University of Oklahoma.

The nation's last EF-5 tornado struck Moore, Oklahoma, on May 20, 2013.

The SWEAT Index evaluates the potential for severe weather by combining several parameters into one index. These parameters include low-level moisture (850 mb dewpoint), instability (Total Totals Index), lower and middle-level (850 and 500 mb) wind speeds, and warm air advection (veering between 850 and 500 mb).

"Significant" is defined as: tornadoes rated EF2 or greater, thunderstorm wind gusts of hurricane force (74 mph) or higher, or hail 2 inches or larger in diameter. The outlook on day 3 combine all forms (tornado, wind, and hail) into a single black hatched area for a 10% or higher significant-severe risk.

High winds, hail, excessive precipitation, and wildfires are forms and effects of severe weather, as are thunderstorms, downbursts, tornadoes, waterspouts, tropical cyclones, and extratropical cyclones. Regional and seasonal severe weather phenomena include blizzards (snowstorms), ice storms, and duststorms.

A hurricane with maximum sustained winds of at least 157 mph is considered to be a Category 5 cyclone on the Saffir-Simpson Hurricane Wind Scale. A Category 5 is the strongest a hurricane can get on the scale, as there is not a Category 6 rating.

Weather-related extreme events are often short-lived and include heat waves, freezes, heavy downpours, tornadoes, tropical cyclones and floods. Climate-related extreme events either persist longer than weather events or emerge from the accumulation of weather or climate events that persist over a longer period of time.

Once you reach categories 4 and 5, it means those storms can do more harm than good (with category 5's considered "primarily hazardous.") An AR5 hit the central California Coast on Dec. 29, 1996, lasting 100 hours and causing over $1 billion in damages.