Winter Returns Across the Northern Tier; Record Warmth for the Southwest

A large high pressure system will usher in cold air for this first day of March across the northern Plains, Great Lakes, Northeast and mid-Atlantic. Some wintry precipitation may evolve across the mid-Mississippi Valley, Ohio Valley and mid-Atlantic through Monday. Meanwhile, record warmth will spread across the Southwest, southern Plains through early this week. 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

Winter Returns Across the Northern Tier; Record Warmth for the Southwest

ZSE SIGMETs