Why Use Convective Outlooks?

Perhaps one of the most underutilized weather products shown on the ForeFlight Map view are the yellow-shaded polygons called convective outlooks. On any given eight-hour shift, they are issued hourly by a highly trained meteorologist at the Aviation Weather Center (AWC) in Kansas City. In fact, convective SIGMETs shown by a red-shaded polygon are also issued by this same forecaster.

wst-outlooks

Convective outlooks, shown in yellow, can be displayed by picking the AIR/SIGMET/CWAs menu selection. Tapping on the TS button will display all convective SIGMETs as well as any convective outlooks.

Let’s start with convective SIGMETs

Convective SIGMETs (WSTs) define regions of airspace with active areas of thunderstorms that meet specific criteria. The important word here is active. In other words, convective SIGMETs represent more of a NOWcast for thunderstorms than a forecast. Here’s the way it works. Each and every hour the convective SIGMET forecaster at the AWC looks for thunderstorms throughout the lower 48 United States and coastal waters that meet specific criteria. A single cell pulse thunderstorm isn’t necessarily hazardous as long as you don’t fly through the same airspace that it occupies. However, when thunderstorms form long lines, are clustered close together in widespread areas, are embedded or severe, they become more of a threat to aviation and the forecaster will issue a convective SIGMET for those areas of thunderstorms at 55 minutes past each hour.

wst-siriusxm

A convective SIGMET outlined in red for a line of embedded thunderstorms as depicted from the SiriusXM satellite weather broadcast.

Despite the fact that convective SIGMETs are valid for two hours when issued, the following hour the forecaster will once again evaluate the convective threat and issue a new round of convective SIGMETs. Each new issuance at 55 minutes past the hour will supersede the previous set of convective SIGMETs. Effectively, no convective SIGMET will ever exist for two hours.

This is not to say that you must fly around convective SIGMET areas. For a convective SIGMET to be issued, the area of convection must contain significant radar echoes that fill a minimum of 40% of the area at least 3,000 square miles or 40% of a line of at least 60 miles in length. This leaves a fair amount of airspace to navigate through some convective SIGMET areas.

What about convective outlooks?

First, they are not “outlook SIGMETs” as I’ve seen them called. In fact, they are not SIGMETs at all. Unlike convective SIGMETs, convective outlooks are truly forecasts; there isn’t a requirement that active thunderstorms exist when they are issued. Instead, they define larger regions of airspace that are expected to contain thunderstorms that meet convective SIGMET criteria in the next two to six hours after the outlook was issued. These may include ongoing areas or lines of convection covered by a convective SIGMET or they may include new areas or lines of thunderstorms that are expected to develop and reach convective SIGMET criteria in the two to six hours valid period.

wst-outlook

A convective outlook is outlined in yellow. This shows the region where convective SIGMETs are likely to be issued within the next two to six hours. The text of the outlook provides the effective time.

That two to six hour window is a perfect “sweet spot” for many of us making flights. There may not be any thunderstorms when you go to depart, but if your proposed route takes you through one of these convective outlook areas in the valid time specified you may see one or more convective SIGMETs issued within this outlook area during your flight.

outlook-with-cwa

When convection doesn’t quite meet convective SIGMET criteria you may still see a Center Weather Advisory (CWA) issued for thunderstorms as shown in this image. CWAs are issued by meteorologists at the Center Weather Service Units and coordinated with forecasters at the Aviation Weather Center.

What about ADS-B or SiriusXM?

At the moment, convective outlooks are not broadcast over the ADS-B ground stations and are not part of the SiriusXM satellite weather broadcast. In ForeFlight, we attempt to preserve the latest convective outlooks until they expire six hours later. So be sure to use the Pack feature of ForeFlight prior to departure.