Convective Outlook

• The SPC Convective Outlook combines maps and a written discussion of expected thunderstorm development and severe-weather threats across the contiguous United States.
  • It is a forecast product, not a radar observation.
• SPC outlooks support planning several days ahead and refining plans as the weather approaches.
  • Longer-range outlooks provide broader severe-weather probabilities because the exact location, timing, and hazards are less certain farther into the future.
  • Nearer-term outlooks provide more detailed guidance.
• Modern outlooks provide categorical maps, probability maps, and a narrative.
  • The forecast day and hazard may be selected rather than treating the product as a fixed Day 1/Day 2 two-panel chart.
• Obtain the full product from the SPC Convective Outlooks page.
  • The Aviation Weather Center (AWC) also displays an SPC outlook layer within Graphical Forecasts for Aviation (GFA); select it in the layers menu.
• SPC national outlooks do not provide equivalent coverage for Alaska, Hawaii, or U.S. territories.
• Severe-weather criteria: A thunderstorm qualifies as severe if it produces any one of the following:
  • A tornado.
  • Damaging winds or wind gusts of at least 50 knots.
  • Hail at least 1 inch in diameter.
• The outlook emphasizes severe convective weather potential from supercells, squall lines, and multicell thunderstorm complexes.
  • Isolated, short-lived thunderstorms can also become severe, including outside an outlined severe-risk area.
• The severe-weather criteria do not define whether a thunderstorm is safe to fly through.
  • Storms below those thresholds can still produce dangerous turbulence, lightning, icing, wind shear, and heavy precipitation.

• Day 1 and Day 2 map overlays include:
  • Categorical — Days 1–3: shows the five severe-weather risk categories, from Marginal through High, with general-thunderstorm areas identified separately.
  • Tornado — Days 1–2: shows the probability of one or more tornadoes.
  • Wind — Days 1–2: shows the probability of damaging thunderstorm winds or wind gusts of at least 50 knots.
  • Hail — Days 1–2: shows the probability of hail at least 1 inch in diameter.
• Day 3 map overlays include:
  • Categorical.
  • Combined severe-weather probability.
• Day 4 - 8 map overlays include:
  • Days 4–8 use separate daily probability maps.
• Severe-weather probabilities apply within 25 statute miles of a point during the valid period. Conditional intensity markings provide additional information about potential strength.

Day 1 Convective Outlook:

• Day 1 provides the nearest-term outlook for general thunderstorms and organized severe convection during its valid period.
• Review the categorical graphic together with separate tornado, wind, and hail probabilities and any conditional intensity areas. The categorical map summarizes the overall threat; it does not identify which hazard drives that risk at every location.
• Read the summary and regional discussion for storm initiation, movement, organization, and timing. Compare them with current observations and later updates as departure approaches.
• For a shorter-period view, consult the separate SPC Thunderstorm Outlooks.
  • These depict general-thunderstorm probabilities over 4- or 8-hour periods, using 10%, 40%, and 70% thresholds within 12 miles of a point. They do not use the severe-outlook 25-statute-mile probability radius.
• Review Mesoscale Discussions for near-term storm development and watch potential; see how these fit into flight planning.
• Open the latest Day 1 Convective Outlook.

Day 2 Convective Outlook:

• Day 2 covers the following forecast day, not the Day 1 period. An outlook issued today covers 1200Z tomorrow through 1200Z two days from today.
• It includes categorical risk, separate tornado/wind/hail probabilities, conditional intensity where forecast, and a discussion.
  • The categorical map also identifies general-thunderstorm areas, separately from the severe-weather risk categories.
• Use it to assess next-day route choices, alternates, and schedule flexibility. Refine those plans with the applicable Day 1 outlook and current aviation weather products as the flight approaches.
• Open the latest Day 2 Convective Outlook.

Day 3 Convective Outlook:

• Day 3 covers the third forecast day. An outlook issued today covers 1200Z two days from today through 1200Z three days from today.
• The product includes categorical risk and a combined probability of one or more severe-weather events: tornadoes, damaging thunderstorm winds, or large hail, rather than the separate hazard-probability maps used on Days 1 and 2.
  • Any one of those hazards qualifies; the probability does not require all three to occur together. General-thunderstorm areas are also shown on the categorical map.
• Read any intensity markings and the discussion for the anticipated severity and uncertainty. Increasing lead time limits confidence in exact storm locations and timing.
• Open the latest Day 3 Convective Outlook.

Days 4–8 Severe Weather Outlook:

• This longer-range product identifies organized severe-weather potential with a separate map for each day and a discussion covering the forecast period.
• Shaded areas use 15% and 30% probabilities of severe weather within 25 statute miles of a point during the selected valid day. Those highlights broadly correspond to Slight and Enhanced risk areas in shorter-range products.
• If no 15% area is outlined, read the explanation:
  • Predictability too low: severe storms may occur, but the location or occurrence is too uncertain to delineate confidently.
  • Potential too low: a 15% or greater severe-weather probability appears unlikely.
• No highlighted area does not mean no thunderstorms. These maps are not a general-thunderstorm forecast and do not resolve a particular airport's weather. Use them for early planning, then reassess with shorter-range products.
• Open the latest Days 4–8 Severe Weather Outlook.

• The five severe-weather categories summarize expected coverage and intensity. They are not counts of expected storm reports and are not aircraft operating categories.
• General thunderstorms (TSTM), shown in light green, identify a 10% or greater thunderstorm probability during the valid period. This is separate from the five severe-weather levels.

• Probability and conditional intensity both contribute to the categorical risk. SPC uses hazard-specific conversion tables; the same percentage can lead to different categories for different hazards or intensity levels. A category is not one universal percentage applied to tornadoes, wind, and hail.
• Slight does not mean slightly severe. A concentrated or uncertain threat can produce a violent storm within a lower-category area. Read the hazard maps and narrative rather than using the category alone.
• Risk contours are forecast boundaries, not protective barriers. Thunderstorms and even severe weather can occur outside an outlined area. The former “SEE TEXT” category and fixed storm-report-count definitions do not describe the current five-level system.

• A severe-weather probability is the forecast chance of one or more specified events within 25 statute miles of a point during the valid period. It is not the percentage of the route covered by storms or the chance of a direct strike on the aircraft.
• For example, a 15% hail area means a 15% chance of severe hail within that distance of a point in the area during the forecast period. It does not mean hail will last 15% of the day.
• Read the selected hazard and legend. A color can represent a different percentage or meaning on tornado, wind, hail, and categorical maps. Days 1 and 2 separate the hazards; Day 3 and Days 4–8 combine severe hazards.
• Do not add tornado, wind, and hail percentages together. The same storm may produce more than one hazard, so their probabilities overlap. Adding map percentages does not calculate the probability of encountering severe weather along a flight route.
• Small tornado probabilities can be substantially above the normal daily probability. Do not dismiss a threat simply because its percentage is numerically small.
• The 25-statute-mile distance describes how the forecast probability is defined; it is not a thunderstorm-avoidance distance. Probability also does not specify the severity of the event if it occurs.

• Since March 3, 2026, Days 1–3 use Conditional Intensity Groups (CIG), also called intensity levels, to better distinguish the strength of severe hazards if those hazards occur.
  • The five categorical risk names remain unchanged.
• Probability answers how likely; intensity answers how strong if it happens. Intensity is based on the expected storm environment and storm type. A low occurrence probability can accompany a high-impact threat.
• The hazard-map legend distinguishes Level 1 with broken diagonal hatching, Level 2 with solid diagonal hatching, and Level 3 with crosshatching. Use the legend actually printed on the product; do not apply the old “10% significant severe” interpretation to the new intensity markings.
• The comparison below summarizes intensity if a hazard occurs, not how likely it is to occur. These are illustrative distributions and reasonable maximums, not strict caps; stronger events remain possible in lower-level areas.
• No intensity highlight does not mean no severe weather. Read the probability shading, discussion, and current SPC probability-to-category tables together. Both coverage and conditional intensity influence the final category.

• Day 3 combined severe-weather maps use levels through CIG2; they do not provide separate tornado, wind, and hail intensity maps.

• Start with the date, forecast day, and valid interval. A label such as Valid 112000Z–121200Z means from 2000Z on the 11th until 1200Z on the 12th; confirm the month and year in the product heading.
• Locate the whole operation: departure, route, destination, alternates, and possible delays. Check which categorical and hazard-probability areas overlap those locations.
• Read the discussion alongside the map. Its usual sections answer different questions:
  • Summary: the main threat areas, hazards, and timing.
  • Synopsis: the larger weather pattern and features supporting development.
  • Regional technical discussion: the reasoning behind local storm coverage, intensity, timing, and uncertainty.
• Example, a 15% hail contour overlaps the route and the discussion expects storms after 2000Z.
  • The contour describes hail potential over the valid period; the discussion helps assess when it may develop. A planned 1900Z arrival is not automatically safe: delays, earlier initiation, and the return flight must be evaluated using current observations and updates.
• If using the text points product, location identifiers and offsets define risk-area polygons. An offset such as 20 NW FMY means 20 nautical miles (NM) northwest of that reference point; this differs from the statute-mile radius used for severe-weather probabilities. ...CONT... indicates continuation along the U.S. border to another listed point.
• Reassess when an update changes the forecast. Expanding coverage, earlier initiation, faster movement, or increasing intensity may eliminate a previously reasonable route or departure window.

• Use the outlook to make early route, departure-time, fuel, alternate, delay, or cancellation decisions. Consider the return flight and the possibility that storms will persist after sunset or block more than one escape route.
• Build the current weather picture using radar imagery, satellite imagery, Terminal Aerodrome Forecasts (TAFs), surface observations, Pilot Weather Reports (PIREPs), and Convective Significant Meteorological Information (SIGMETs).
  • Outlook: broad potential for future convection.
  • Mesoscale Discussion: analysis of developing conditions, usually emphasizing the next 1–3 hours, including possible watches or changes to existing threats.
  • Severe thunderstorm or tornado watch: conditions favor the specified hazard over the watch area.
  • Warning: the specified hazard is occurring or imminent, based on observations or radar evidence.
  • Convective SIGMET: a separate aviation advisory for qualifying hazardous convection.
  • These products do not have to appear in a fixed sequence. Do not wait for a watch, warning, advisory, or higher outlook category before avoiding a developing storm.
• Every thunderstorm is hazardous to aircraft, including storms labeled non-severe. Review thunderstorm hazards and avoidance; forecast risk categories do not establish an acceptable penetration threshold.
• Plan broad avoidance rather than threading gaps. The Federal Aviation Administration (FAA) Aeronautical Information Manual advises avoiding any severe thunderstorm or one giving an intense radar echo by at least 20 miles. Datalink radar is delayed and should support strategic avoidance, not close-in maneuvering between cells.
• Keep the products distinct: the SPC outlook describes thunderstorm/severe-weather risk; the GFA thunderstorm display and the Traffic Flow Management (TFM) Convective Forecast (TCF) use their own coverage and forecast criteria. They complement one another and are not interchangeable maps. AWC GFA guidance explains the available layers.