National Weather Service United States Department of Commerce

Heavy Rain Threat Along Central Gulf Coast; Severe Weather Possible Across Upper Midwest

Heavy rainfall remains likely along the central Gulf Coast through Friday, from southeast Louisiana to the Florida Panhandle. This rainfall may be excessive and produce flash flooding across the saturated region. Meanwhile, a strong cold front will push into the Upper Midwest and may trigger severe thunderstorms today. These storms may contain hail and damaging winds from Minnesota to Nebraska. Read More >

Seattle, WA

Center Weather Service Unit

ZSE SIGMETs

Weather.gov > Seattle, WA > ZSE SIGMETs

 

 

 


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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