NWS Morristown TN - Advisory and Warning Criteria

The following are the Criteria used by the National Weather Service office in Morristown, TN to issue Advisories & Warnings. Watches are generally issued with longer lead times in expectation of meeting Advisory and/or Warning criteria.

 

SEVERE WEATHER

Severe Thunderstorm Warning Tornado Warning

Hail

> 1.00”

AND/OR

Wind

> 58 mph (50kts)

AND/OR

Significant Wind Damage, i.e., Trees down, large tree limbs down, structural damage to buildings.

Tornado

A violently rotating column of air in contact with the ground,

indicated by either radar or report.

 

WINTER WEATHER

Winter Weather Advisory Winter Storm Warning Ice Storm Warning  Blizzard Warning Wind Chill Warning  Wind Chill Advisory

Snow

1" to 3” in 12 hours*

OR

Freezing Rain & Sleet

Ice accumulation < 0.25”

OR

at the forecaster's discretion

Snow

4" or more in 12 hour

OR

Snow

> 6.00” in 24 hours

OR

Freezing Rain & Sleet

Ice accumulation > 0.25”

Ice accumulation

> 0.25” in 12 hours

Visibility

< ¼ mile

AND

Sustained Winds or Frequent Gusts

> 35mph for at least 3 hours which is accompanied by either snow or blowing snow

Temperature

< -15°

AND

Winds

> 10 mph for at least 3 hours

Temperature

between -5° to -14°

AND

Winds

> 10 mph for at least 3 hours

               

NON-PRECIPITATION HAZARDS

High Wind Warning Wind Advistory Dense Fog Advisory  Dense Smoke Advisory Freeze Warning Frost Advisory Excessive Heat Warning Heat Advisory 

Sustained Winds

> 40 mph for at least 1 hour

AND/OR

Wind Gusts

> 58 mph for any duration

Sustained Winds

26 to 39 mph for at least 1 hour

AND/OR

Wind Gusts

between 40 and 57 mph for any duration

Visibility

< ¼ mile over a large area

Visibility

< ¼ mile over a large area

Temperature

< 32° for areas still in Freeze program

Temperature

33° to 36° during defined growing season

Daytime Heat Index

>  110°

AND

Nighttime Low Temperature

> 75° for at least 2 days

Daytime Heat Index

> 105°

AND

Nighttime Low Temperature

> 75° for 1 to 2 days


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.