SKYWARN is the  Identification, Evaluation, and Reporting of Dangerous Weather

Milwaukee Area Skywarn Association
MASA  ("May-sah")  a Wisconsin Registered Non-profit and I-R-S 501c3 Tax Exempt Corporation

CHEAT SHEET OF FREQUENT WEATHER TERMS
 

EVENT

THRESHOLDS

WARM SEASON
 Flash Flood Warning Flooding that produces life and property threat within 6 hours
 Flood Warning Flooding that produces life and property threat within 6-12 hours.
 Flood Warning (Mainstream river) Flooding that produces life and property threat beyond 12 hours.
 HIGH RISK of severe thunderstorms A High risk area almost always means a major severe weather outbreak is expected, with great coverage of severe weather and enhanced likelihood of extreme severe (i.e., violent tornadoes or extreme convective wind events over a large area). Within a high risk area, expect at least 20 tornadoes with at least 2 of them rated F3+, or an extreme derecho causing 50+ widespread wind events (50+) with numerous higher end wind (80+ mph) and structural damage reports
 MODERATE RISK severe thunderstorms A Moderate risks imply a greater concentration of severe thunderstorms, and in most situations, greater magnitude of severe weather. Within a moderate risk area, at least 30 reports of hail 1 inch or larger, or 6-19 tornadoes, or numerous wind events (30 that might be associated with a squall line, bow echo or derecho) are forecast
 Severe Thunderstorm Warning WINDS >= 50 Kts/58 Mph (or implied by damage), and/or HAIL >= 3/4 inch.
 SLIGHT RISK severe thunderstorms A Slight risk implies well-organized severe thunderstorms are expected but in small numbers and/or low coverage. Within a slight risk area, 5-29 reports of 1 inch of larger hail, and/or 3-5 tornadoes, and/or 5-29 wind events are forecast.
 Tornado Warning A tornado sighted by spotters or imminent based on radar.
 Urban-Small Stream Advisory Inconvenience flooding 0-24 hours.
   

MARINE EVENTS
 Gale Warning Sustained winds 34-47 Kts for many hours.
 Lake Shore Warning Significant lakeshore flooding, erosion, ice jam, or seiche.
 Small Craft Advisory Winds 18-33 Kts and/or waves >= 4 feet.
 Special Marine Warning Thunderstorm winds>=34 Kts for<= 2hrs.
 Storm Warning Sustained winds >= 48 Kts
   

COLD SEASON
 Blizzard Warning or
 Ground Blizzard Warning		 Sustained winds or Frequent gusts >=35 Mph & falling or blowing snow with
visibility < 1/4 mile >= 3 hours. (Only Blowing snow for ground blizzard.)
 Blow Snow-Drifting Snow Advisory Wind driven snow, intermittent visibility occasionally < = 1/4 mile.
 Freezing Rain-Drizzle Advisory Light freezing rain/drizzle with ice accumulations < 1/4 " in 12 hours or less.
 Heavy Snow  Warning Heavy Snow, 6" within 12 hours, or 8" within 24 hours and light winds.
 Ice Storm Warning Ice accumulations > = 1/4" in 12 hours or less.
 Lake Effect Snow Advisory Lake effect snow squalls; 3-6 inches in 12 hours or less.
 Lake Effect Snow Warning 6" of heavy snow showers/squalls within 12 hours, or 8" within 24 hours.
   
 Wind Chill Warning  Wind chills 35 below or colder w/ winds 10 MPH or greater for  3 hours.
   
 Winter Weather Advisory  One or more of the following <=12 hrs unless stated:
-3 to 6" snow or more (8" in 24 hrs)
-Freezing rain(< 1/4 inch with another event).
-Sleet Accumulations <2" or more.
-Blowing snow reducing visibility to <1/2 mile and winds < 25MPH.
 Winter Storm Warning  One or more of the following <=12 hrs unless stated:
-6" snow or more (8" in 24 hrs)
-Freezing rain(< 1/4 inch with another event).
-Sleet Accumulations 2" or more.
-Blowing snow reducing visibility to <1/2 mile and winds 25-34 MPH.
  Copyright 2003-2008 Milwaukee Area Skywarn Association.
NON-PRECIPITATION
 Air Stagnation Advisory Major buildup of air pollution, smoke, dust, gases, (visibility < 1/ mile??)
 Dense Fog Advisory Widespread visibilities < 1/4 mile.
 Excessive Heat Warning Any 24 hour period...Heat Index >=115 degrees during day and >= 80 at night.
 Freeze Advisory In growing season; widespread temps <= 32 degrees.
 Frost Advisory Widespread frost in growing season, temps 33-39 degrees.
 Heat Advisory Any 24 hour period... Heat Index >=105 degrees day and >= 80 at night
 High Wind Warning Sustained winds >= 40 MPH for 1 hour or more, or any gust >= 58 MPH.
 Wind Advisory Sustained winds >=30 MPH for 1 hour or more, or any gust 45-57 MPH.
 Wind Chill Advisory Wind chills <= minus 35 with winds > 10 MPH.
 Wind Chill Warning Wind chills <= minus 50 with winds > 10 MPH.
   
   
 

 
Copyright: MASA Inc. 2003-2008