Some NWS ILN Product Definitions

 

Sky Cover:

CLOUDY 9/10 to 10/10 opaque clouds

MOSTLY CLOUDY 7/10 to 8/10 opaque clouds

CONSIDERABLE CLOUDINESS 7/10 to 8/10 opaque clouds

PARTLY CLOUDY 3/10 to 6/10 opaque clouds

PARTLY SUNNY 3/10 TO 6/10 opaque clouds

MOSTLY CLEAR OR MOSTLY SUNNY 1/10 TO 3/10 opaque clouds

CLEAR OR SUNNY 0/10 to 1/10 opaque clouds

 

Precipitation Percent Wording:

20 Percent...WIDELY SCATTERED or SLIGHT CHANCE

30 to 50 Percent...SCATTERED or CHANCE

60 to 70 Percent...LIKELY

80 to 100 Percent...NUMEROUS, PERIODS, OCCASIONAL or No Descriptor (ie, RAIN., SNOW.)

 

Snowfall/Sleet:

Most of CWA...

Winter Weather Advisory(snow/sleet)...2 inches in 24 hours (Occuring or Imminent)

Winter Storm Warning(snow/sleet)...4 inches or more in 24 hours (Occuring or Imminent)

Winter Storm Watch...4 inches in 24 hours (Expected to begin in more than 12 to 24 hours)

Mercer, Auglaize, Shelby, Logan and Hardin Counties...

Winter Weather Advisory(snow/sleet)...4 inches in 24 hours (Occuring or Imminent)

Winter Storm Warning(snow/sleet)...6 inches or more in 24 hours (Occuring or Imminent)

Winter Storm Watch...6 inches in 24 hours (Expected to begin in more than 12 to 24 hours)

 

Mixed Precipitation:

Winter Weather Advisory(Freezing Rain)... < 1/4 inch ice accumulation (Occuring or Imminent)

Winter Storm Warning(Freezing Rain)... 1/4 inch or more of ice accumulation (Occuring or Imminent)

Winter Storm Watch(Freezing Rain)...1/4 inch or more of ice accumulation (Expected to begin in more than 12 to 24 hours)

 

Wind Chill:

Wind Chill Advisory...Wind chills minus 20 to minus 34 degrees (wind >10 mph)

Wind Chill Warning...Wind chills minus 35 degrees or lower (wind >10 mph)

 

Winds:

Sustained Wind Speed(MPH) Descriptive Term in Body of Zones:

0 to 5 LIGHT WIND (do not mention speed in zones)

5 TO 10 None

10 TO 15 None

AROUND 10 None

10 TO 20 None

15 TO 20 BREEZY (warm season)

BRISK/BLUSTERY (cold season)

15 TO 25 BREEZY (warm season)

BRISK/BLUSTERY (cold season)

20 TO 30 WINDY

25 TO 35 WINDY

30 TO 40 STRONG/DAMAGING WINDS

ABOVE 40 STRONG/DAMAGING WINDS

 

Wind Headlines:

Wind Advisory...Sustained wind 31 to 39 mph and/or wind gusts 46 to 57 mph for one hour or more (Occuring or Imminent)

High Wind Warning...Sustained wind 40 mph and/or wind gusts 58 mph or higher for one hour or more (Occuring or Imminent)

High Wind Watch...Sustained wind 40 mph and/or wind gusts 58 mph or higher for one hour or more (Expected to begin in more than 12 hours)

 

Frost/Freeze:

Frost advisory...non-killing frost, typically with low temperatures near or slightly above freezing under good radiational cooling conditions (i.e. little or no wind).

Frost warning...widespread hard frost with temperatures below 32 under good radiational cooling conditions (i.e. little or no wind).

Freeze warning...freezing temperatures with lows below 32 under CAA (i.e. surface wind, no frost) or radiative cooling (no surface wind, frost) situations.

 

Excessive heat:

Excessive Heat Warning...Heat Index > 115 degrees for any period or 105 for 3 hours or more for 2 consecutive days (Occuring or Imminent)

Excessive Heat Watch...Heat Index > 115 degrees for any period or 105 for 3 hours or more for 2 consecutive days (Expected to begin in more than 12 to 24 hours)

Heat Advisory...Heat Index between 105 and 115 for 3 hours or more

 

Fog/Dense Fog:

Dense Fog Advisory...Widespread areas of fog reducing visibility to less than 1/4 mile

 

Heating/Cooling Degree Days:

Heating Degree Days...The number of degrees the mean daily temperature is below 65 degrees

Example: High 60 degrees, Low 40 degrees = Mean Temperature of 50 degrees --> 15 HDD

Cooling Degree Days...The number of degrees the mean daily temperature is above 65 degrees

Example: High 95 degrees, Low 75 degrees = Mean Temperature of 85 degrees --> 20 CDD