Heat Across the Center of the Nation; Severe Thunderstorms Across the Great Lakes and Ohio Valley

Heat expands across the Desert Southwest, Plains, Mississippi Valley and Midwest into Monday. Fire weather concerns continue for portions of the Intermountain West. Active monsoonal moisture fuels thunderstorms over the Southwest with possible flash flooding. Tropical cyclone Fausto in the Pacific, should weaken as it approaches Hawaii; Dangerous surf, swells and rip currents are expected. Read More >

Text of all SIGMETs Around Contiguous Western US

None Found

Description of Convective and Non-Convective SIGMETs

SIGMETs are Inflight Weather Advisories for Significant Meteorological hazards. A SIGMET is "widespread" in that it covers an area of at least 3,000 square miles. Note that the particular hazard may be present in only a small portion of the area at any particular time. SIGMETS are issued for:

Severe Icing (not associated with thunderstorms -- otherwise, it is a Convective SIGMET)
Severe Turbulence (similarly, only if not associated with thunderstorms)
Duststorms and sandstorms lowering visibility to less than three miles
Volcanic Ash

Convective SIGMETs are issued for severe convective activity, which implies severe turbulence, severe icing, and low-level wind shear. Specifically:

Embedded thunderstorms
A line of thunderstorms
Thunderstorms with heavy precipitation affecting 40%+ of an area at least 3,000 square miles
Surface winds 50+ knots due to severe thunderstorm
Hail 3/4+ inches in diameter
Tornadoes

Map of SIGMETs (including International)

ZSE RSS Feed

Heat Across the Center of the Nation; Severe Thunderstorms Across the Great Lakes and Ohio Valley

ZSE SIGMETs