Lala Impacting Hawaii; Severe Thunderstorm and Flash Flooding Risks; Excessive Heat

Areas of gusty winds, heavy rain leading to flash flooding, and high surf continue across portions of Hawaii as Tropical Storm Lala continues to move away from the islands. Severe thunderstorm, heavy rainfall, and flash flooding threats continue from the Midwest to the Mid-Atlantic and across the central High Plains. Record heat continues for areas of the central/southern Plain into the Southeast 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)

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Lala Impacting Hawaii; Severe Thunderstorm and Flash Flooding Risks; Excessive Heat

ZSE SIGMETs