Ok, So What Is Criteria Weather?
There is a "default" set of criteria nationwide, and then there are specific criteria set by individual NWS offices. For example, this is the list of "Criteria Weather" for the Phoenix warning area:
Again, this is just for the Phoenix area.
- Tornado
- Funnel Cloud
- Storm Damage (deaths, injuries, broken tree limbs, shingles off roofs, etc.)
- Flooding (streets, running washes, etc.)
- Low Visibility
- less than 1 mile due to dust, sand, fog, etc. (not rain though)
- Microburst
- visual confirmation of ‘toe’/ ‘foot’ feature
- Rotating Wall Cloud
- Heavy Rainfall
- measured ½ inch or more accumulation in 30 minutes or less
- Hail (diameter of largest stone - any size)
- Snow (accumulating or not)
Again, this is just for the Phoenix area.
The following default criteria are what spotters should look for when phoning in their reports. They should always call the responsible Weather Service Office when any of the below are noted:
SPOTTERS SHOULD NOT CALL NWS PERSONNEL WITH ROUTINE WEATHER OR FOR FORECASTS!!
- TORNADO (on the ground) or FUNNEL CLOUD (tail not touching the ground)
- ROTATING WALL CLOUD
- WIND (estimated or measured at 40 mph or more)
- MICROBURST (visually identified)
- RAINFALL (1/2 inch (.50) or more in 30 minutes)
- FLOODING (of any kind)
- DAMAGE and/or DEATHS and/or INJURIES due to the weather event
- HAIL (1/2 inch (.50) diameter, or greater)
- VISIBILITY (less than 1/4 mile due to fog, dust, blowing snow or ash)
- SNOWFALL (accumulating at a rate of 1 inch or more per hour)
SPOTTERS SHOULD NOT CALL NWS PERSONNEL WITH ROUTINE WEATHER OR FOR FORECASTS!!
How To Report What You Saw
Your severe weather report should be detailed but concise, and should address the following questions:
WHAT did you see?
WHERE did you see it? Report the location/approximate location of the event. Be sure to distinguish clearly between where you are and where the event is thought to be happening (“I’m 5 miles north of Mayberry. The tornado looks to be about 5 miles to my northwest”).
WHEN did you see it? Be sure that reports that are relayed through multiple sources carry the time of the event, NOT the report time.
Any other details that are important - How long did it last? Direction of travel? Was there damage? etc.
WHAT did you see?
WHERE did you see it? Report the location/approximate location of the event. Be sure to distinguish clearly between where you are and where the event is thought to be happening (“I’m 5 miles north of Mayberry. The tornado looks to be about 5 miles to my northwest”).
WHEN did you see it? Be sure that reports that are relayed through multiple sources carry the time of the event, NOT the report time.
Any other details that are important - How long did it last? Direction of travel? Was there damage? etc.
Is Criteria Weather The Same Everywhere?
Every NWS office has it's own criteria. While they all follow the listing above, some have more specific, or regional criteria, as well. Make sure you know the criteria for your area before you report in!
The National Weather Service office in Flagstaff publishes this set of reporting criteria for summer and winter:
The National Weather Service office in Flagstaff publishes this set of reporting criteria for summer and winter:
Page Last Updated, 07/28/18
