Rapid Warm-Up Forecast Across Much of the Lower 48 Today and Tuesday

Most of the U.S. starts the week calm and unseasonably warm. The Heartland will be warmest, with highs 25–30° above average. Only the Gulf Coast stays chilly. Rain today is limited to western Washington while lake effect snow continues east of Lake Ontario. Cooler air returns after Tuesday, bringing a wintry mix to the Midwest and Northeast by Wednesday. 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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Rapid Warm-Up Forecast Across Much of the Lower 48 Today and Tuesday

ZSE SIGMETs