Skywarn

Watch, Warning, and Advisory Definitions

Recent Watches/Warnings/Advisories for Southeast Michigan

Basic Definitions:

The National Weather Service issues a variety of products to keep our customers informed of unusual, inconvenient and hazardous weather conditions. A multi-tier concept is employed to accomplish this task with Outlooks, Watches, Warnings and Advisories to point out specific conditions.

Outlook: Used to give considerable lead time that a hazardous event may develop in the next 7 days.

Watch: Issued when the risk of a hazardous weather or hydrologic event has increased significantly, but its occurrence, location, and/or timing is still uncertain. It is intended to provide enough lead time so those who need to set their plans in motion can do so.

Warning: Issued when a hazardous event is occurring or has a very high probability of occurrence. Warnings advise of a threat to life or property.

Advisory: Issued when a hazardous event is occurring or has a very high probability of occurrence. Advisories describe events that cause significant inconvenience.

CONVECTIVE EVENTS - PRODUCT	THRESHOLDS
SEVERE THUNDERSTORM WARNING - SVR	Winds 50 kts (58 mph or implied by damage), and/or hail 1 inch or greater
TORNADO WARNING - TOR	Tornado occurring or developing
SEVERE THUNDERSTORM WATCH - WCN	Thunderstorms capable of Winds 50 kts (58 mph or implied by damage), and/or hail 1 inch or greater. Issued by SPC, 0-8 hours.
TORNADO WATCH - WCN	Thunderstorms capable of producing tornadoes. Issued by SPC, 0-8 hours.
SIGNIFICANT WEATHER ALERT - SPS	Winds 40+ mph (35 kts), hail 1/2 inch or greater and/or frequent/continuous lightning

HYDRO & LAKESHORE EVENTS - PRODUCT	THRESHOLDS
FLOOD WATCH - FFA	Possible long duration flooding over a general area more than 6 hrs after main rainfall
FLASH FLOOD WATCH - FFA	Possible short/long duration flooding over a general area less than 6 hrs after main rainfall
LAKESHORE FLOOD WATCH - CFW	Possible flooding affecting homes, businesses, or roads along the lakeshore within the next 1-3 days
FLASH FLOOD WARNING - FFW	Flooding that produces life/property threat in 0-6 hrs
FLOOD WARNING - FLW	Flooding that lasts 6 hrs or more over a general area and/or affects mainstem rivers that is a threat to life/property
LAKESHORE FLOOD WARNING - CFW	Flooding affecting homes, businesses, or roads along the lakeshore within the next 0-48 hours
FLOOD ADVISORY- FLS	Inconvenience flooding in 0-24 hrs
LAKESHORE FLOOD ADVISORY - CFW	Flooding affecting beaches, docks, marinas, and watercraft along the lakeshore within the next 0-48 hours

MARINE EVENTS - PRODUCT	THRESHOLDS
SPECIAL MARINE WARNING - SMW	Winds (convective or non-conv) 34 kts for 2 hrs or less, hail 3/4 inch and/or waterspouts
GALE WARNING - MWW	Sustained winds 34 to 47 kts or freq gusts 34 to 47 kts expected within 24 hours
STORM WARNING - MWW	Sustained winds 48 to 64 kts or freq gusts 50 to 64 kts expected within 24 hours
HURRICANE FORCE WIND WARNING - MWW	Sustained winds 65+ kts expected within 24 hours
HEAVY FREEZING SPRAY WARNING - MWW	Heavy freezing spray is expected within 24 hours
MARINE WATCH - MWW	Issued when warning criteria (except SMW) is expected within 72 hours
MARINE WEATHER STATEMENT - MWS	Winds (convective or non-conv) <34 kts, hail <3/4 inch, and/or thunderstorms
LOW WATER ADVISORY - MWW	Water is expected to be several inches below chart datum for an extended period of time - Consider when an NPW is in effect for High Wind - Issue when Gale Warning is in effect for Saginaw Bay - Coordinate with WFO CLE for Michigan waters of Lake Erie - Water falls below 36" on Detroit River at Gibralter
SMALL CRAFT ADVISORY - MWW	Winds 22-33 kts and/or waves > 3 ft - Nearshore Waters Only
DENSE FOG ADVISORY - MWW	Widespread vsby 1 mile or less

COLD-SEASON EVENTS - PRODUCT	THRESHOLDS
WINTER STORM WARNING - WSW	☞ Heavy snow: Heavy snow including lake-effect with winds less than 35 mph - 8 inches within 12+ hours - 6 inches within 8 hours ☞ Mix: A combo of 2 or more of the following: heavy snow, sleet, freezing rain/drzl ☞ Forecaster Discretion: Winter Storm Warn for lesser amts in shorter time pd w/ blwg snow ☞ Heavy sleet: Sleet accums of 3+ inch in 12 hours or less
SNOW SQUALL WARNING - SQW	Snow squalls reducing visibility to 1/4 mile or less, for 15 minutes or more, on dry frozen highways
BLIZZARD WARNING - WSW	Sustained winds or freq gusts 35+ mph and falling/blowing snow with vsby near 1/4 mile or less for 3 hrs (only blowing snow needed for ground blizzard)
ICE STORM WARNING - WSW	Ice accum over 1/4 inch in 12 hours or less
WIND CHILL WARNING - WSW	Wind chills or air temperature 25 below or colder
WINTER STORM WATCH - WSW	Issued when Warning criteria is expected 12-72 hours in the future
WINTER WEATHER ADVISORY - WSW	☞ Snow (including lake-effect): - >4 inches but <8 inches in 12+ hours - >2 inches but <6 inches in less than 8 hours ☞ Light freezing rain or freezing drzl with ice accum < 1/4 inch in 12 hr or less ☞ Mix: Mix of snow, sleet, freezing rain/drizzle ☞ Sleet: Sleet accums 1/2 to 3 inch in 12 hours or less ☞ Snow & blowing/drifting snow: Wind driven snow, blowing snow, intermittent vsbys 1 mile or less for 3 hours or more with winds 25 to 34 mph ☞ Blowing snow: Blowing snow reducing vsbys to 1 mile or less with winds < 35 mph
WIND CHILL ADVISORY - WSW	Wind chills or air temperature 15 to 24 below for 2 or more hours
WINTER STATEMENT - SPS	- Warning/Advisory in effect: issued to highlight area of heaviest snow, sleet, or freezing rain/drizzle in next 2-4 hours - No Warning/Advisory in effect: issued to highlight area of snow, or sleet, or freezing rain/drizzle causing localized travel impacts in next 2-4 hours

NON-PRECIP EVENTS - PRODUCT	THRESHOLDS
HIGH WIND WARNING - NPW	Sustained winds 40+ mph (35 kts) for 1 hr or more, or any gust 58+ mph (50 kts)
EXCESSIVE HEAT WARNING - NPW	A 3 hr period of Heat Index 105 or more; continue into the night with Heat Index around 80 or more. Can be issued at lower heat index values for consecutive days of excessive heat.
RED FLAG WARNING - RFW	Winds 15+ mph (20 ft level on NFDR sites), RH 25% or lower, temps 75+F, and critically dry fuels combine to produce extreme fire danger and/or fire behavior within 24 hours in coordination with governement land management agencies
FREEZE WARNING - NPW	During growing season, widespread temps of 32 F or less
RED FLAG WATCH - RFW	Issued when Red Flag Warning criteria is expected 24 to 48 hours in the future
NON-PRECIP WATCH - NPW	Issued when Warning criteria is expected 12-48 hours in the future
AIR STAGNATION ADVISORY - NPW	Major buildup of air pollution/particulate due to stable atmos. conditions (initiated by Michigan EGLE)
HEAT ADVISORY - NPW	A 3 hr period of Heat Index 100 or more; continue into the night with Heat Index around 80 or more. Can be issued at lower heat index values for consecutive days of excessive heat.
WIND ADVISORY - NPW	Sustained winds 30+ mph (26 kts) for 1 hr or more, or any gust 45+ mph (39 kts)
DENSE FOG ADVISORY - NPW	Widespread vsby 1/4 mile or less for 3 hours or more
DENSE SMOKE ADVISORY - NPW	Smoke producing widespread or localized vsby 1/4 mile or less
BLOWING DUST ADVISORY - NPW	Widespread/localized vsbys less than 1 mile for 3 hrs or more with sustained winds 25 mph
FREEZING FOG ADVISORY - NPW	Fog, usually with vsby 1/2 mile or less, freezing on cold objects with deposits resulting in impact to commerce, transportation, people, etc.
FROST ADVISORY - NPW	During growing season, widespread frost (temps usually 33-37 F)
DENSE FOG - SPS	Vsby 1/2 mile or less